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5,256 Posts
Discussion Starter · #1 · (Edited)
GM Gen III/IV V8 5.3 Scout II

Here's some of the info on the Gen III 5.3 swap into a International Scout II. It might help with other vehicles as well.

This info covers the GM Gen III V8's: Vortec 4.8/5.3/6.0/6.2 and LS1/2/3/6/7/9. And is by no means complete. It's just a guide and info for the cost benefit analysis for anybody thinking about the swap.

RPO codes for Gen III/IV LS1,2,3, LQ4/9 etc...

The list is for a Gen III truck engines. But the LS car engines and Gen IV engines are the same basic engines.


1) EXHAUST You will need stock F-body LS1 Camaro exhaust manifolds 1998-2002. The stock trucks will not fit the frame they kick out at the exhaust flange! I got mine for free a local shop had thrown them in a dumpster because they said they did not need them. Check E-bay, or locally. Don't pay more than 100 bucks more like 50 bucks for both! Oh, size at least dual 2.5'' back with a cross-over fwd of the transmission with (insert your mufflers here). Single exhaust will work I would do 2.5'' to muffler than a single 3'' or 3.5'' out. As for headers Longtubes are the way to go. But since nobody makes longtubes for the scout swap. I have been looking at some Jeep LT's for GEN III swaps in those they may fit with out mods. I have yet to see if they will fit though. UPDATE: 2010 up Camaro L99/LS3 manifolds work as well. Make sure to get the flange as well.

2)VSS The computer needs a Vehicle Speed Sensor (VSS) signal for shifting the 4L60E and to get the motor to idle right in certain conditions. If running a manual trans you need some type of VSS for the ECM as well for better economy and idle. The stock location for the VSS is in the transfer case on 4x4's. It uses the VSS for the computer and speedo. Options are the 1990 to 1991 NP241 right drop with VSS but you may have to change the ring and the sensor to the late model stuff just check to see if it has the 40 tooth ring on it. Just make sure that VSS is at the end of what ever gear reduction you have of the engine may idle funny and the trans not shift right when in low range! VSS information
The engine can be tuned to run without a VSS but I wouldn't recommend it expect for off road use only. As it reduces fuel mileage.

3) Fuel The engine needs 58-60psi give or take to run correctly. I made a custom tank out of Aluminum for the stock scout location and used the stock gm intank pump and sender truck pump for the same year as the motor. I had to shorten the sender float so it would fit the tank and read correctly. I wanted a little more than the stock 19 gals but the 33 gal is to big so the tank holds 25 gals. Options are a external pump mounted low on the frame rail with a return from the engine to the tank. The late 04 and 2005-up truck fuel rails use a return less fuel system like some of the cars do, so you need a regulator like the Vette fuel/regulator or stock fuel GM truck sender. In the stock returnless fuel systems for the trucks the regulator is in the tank with the pump and sender. On the earlier return style truck intake manifolds, just run a filter and a return line. Summit sells Russell slip on fitting adapters to connect the rail to AN fittings. Make sure to get the screw on versus the clip style. As they are much safer ad positivity secure the fitting to the rail.

4) Emissions I don't run any kind of emissions on my engine. So if your state says you do, than you need to run cats and EGR valve. But if not than you can cap the EGR valve at the intake and exhaust and remove the valve on pre 03 engines the later 2003 plus engines don't have EGR vavle. And I don't run charcoal canister or a purge valve for the gas tank. You most have some one remove the emissions codes in the computer or the check engine light will be on. O2 sensors the stock truck has four two in front of the cats (you need these) and Two behind the cats (can be removed and code turned off). The computer just uses those two behind the cat to see if the cats are working or not. So they can be deleted.

5) Cooling I bought a universal Chevy style radiator from summit that fits the scout opening. I modified the stock GM truck hoses to fit the rad. There is a small hose than goes into the stock rad and a heater for the throttle body I removed for a cooler air intake. It Uses this to prevent throttle ice in cold air but round here it doesn't get that cold. Also on the LS motors you can cap the rear lines and just use the front steam ports. Fan I use an Electric fan because I mounted the engine low and the stock gm fan is to low plus the e-fan doesn't steal horse power! I also run a trans cooler and oil cooler under the AC evap.

6) Computer and wiring I used the stock computer and had it modified with HPtuners to work for what I needed. It's reprogrammed for performance. You will have to go in to the computer and defeat the anti theft software (VATS) so the engine will run in the scout. VATS uses the stock gm ignition switch to tell if it's in the right truck or not! For wiring I interfaced the stock gm harness to my own home made harness for the dash with auto meter gauges. I also put a check engine light (yellow LED) in the dash and put an OBD II plug under the dash so I can plug up My laptop. Options are to interface the gm harness with painless universal. I would recommend pulling all stock scout wires if the are the original old ones not worth a fire! I will try to compile a list of codes to turn off and make a harness interface guide as to what pins do what from the computer I have see them on line but A good shop manual for the gm stuff as wire prints in them. Oh you must also wire the brake light switch up so the torque converter will lock and unlock. I also used the stock Gm Neutral safety backup light switch on the trans at the shift lever. Also if you get the under hood GM fuse block as well as the TAC box and gas petal, this will make swaps easier for DBW TB.

Basically what can be removed or not needed

-EGR: mounts in front of pass. head on exhaust manifold with a tube running from the exhaust manifold to the valve then into the intake behind the TB. This for 03 and earlier motors mostly. Most use a freeze plug as the factory GM plug has been discontinued.

-Canister purge valve/lines: These run from the charcoal canister to a valve on top on the intake behind the thorttle body. Remove the valve and ether plug or JB weld the small hole.

-Cats: catalytic converters you don't need them.

-Rear O2's: These are mounted behind the cats (2 each) and tell the PCM if the cats are working or not. you don't need these.

-Oil level sensor: It's on the pass. of oil pan. You can jumper the wires in the harness at that plug. I usually leave it installed. Or you can remove the sensor and plug with a metric oil drain plug M20x1.5mm threads. Common at most auto parts houses.

-TB heater:
Coolant tubes in the TB that move coolant through the TB to heat it to prevent TB ice. Just remove the lines from the TB bypassing it and reconnect it to the radiator or top rad hose.

The harness can be reworked to remove these things and make it for a 3 or 4 wire hook up to the vehicle. Then have the PCM tuned to remove what you don't need.

Sensor locations (Gen III truck motor)
-MAP is on top of the intake, towards the rear.

-Knock sensors are under the intake but the connector is just to the driver side of the MAP sensor on the intake. (Gen IV motors are on the each side of the block)

-Coolant temp is in the front of the driver side cylinder head.

-Oil pressure is right next to the Cam sensor at the back block behind the intake.

-Low oil level mounted on the pass or oil pan

-EVAP purge solenoid The cylinder sticking out of the intake right in back of the throttle body is the EVAP purge solenoid.

-TPS and IAC are on the cable throttle body. IAC on top. DBW TB has no IAC.

-MAF and IAT are combined in the MAF located on the intake tube.

-Cam sensor Back of the block on Gen III motors and is mounted on the front of the timing cover on Gen IV motors.

-Crank Trigger Located on pass. of block inboard of the starter. Gen III motors are 24x wheel and Gen IV are 58x wheel (save for the early LS2's 05-06 these were Gen IV motors with E40 ECM and 24x wheel's). Black color is 24x reluctor and grey one is 58X reluctor

DBW components
The TAC module (Throttle actuator control) has two connections, one for the pedal harness..other hooks into main engine harness there are two styles the 9-pin connector the later ones are 6-pin.

TAC modules have to match up to the year range of the PCM AND the throttle body.

03-05 TAC module works with 03-05 truck TB and 03-05 PCM (BLUE/GREEN connectors)

01-02 TAC module works with 01-02 truck TB, 97-04 Vette TB, and 01-02 PCM (BLUE/RED connectors).

03-05 TAC modules have an aluminum mounting base, 01-02 TAC modules are all black plastic including the mounting base.

7) Engine mounts I used Advance Adapters universal small block Gen I adapters and weld to the frame and adapted the engine mount to fit the gen III with a plate. I was to lazy to make my own mount the AA stuff is great. The Gen I motors have Three mount holes on the side of the block. The GEN III has four. I weld a steel plate to their mount and used one hole and weld the rest to the plate and drilled the other holes and bolted all four holes to the engine, GRADE 8 Metric bolts are a must. I custom made the trans mount with a hump fro the front shaft.

8) Driveshafts I used JB conversion slip yoke eliminator on the transfer case I run a cv front and rear. The rear shaft will be short with out the SYE like 24 inches but I gained 6 inches in the SYE conversion. Custom shaft rear and stock 86 blazer front lengthened a little.

9) Air conditioner I used the stock gm 99 air compressor and adapted it to work with the scout stuff the compressor fits with just enough room to bolt the hoses on. I had to bend the stock hose to the run them right than adapt them to the IH stuff with adapters. it could still be use as trail air if you don't need the AC. Note the later Gen IV E38/E40/E67 ECM's won't control the a/c system. SO it to needs to be standalone if using 2007-up motor.

10)Intakes The truck intake flow the same as the LS1 car and offers better low end over the car one. The LS6 flows better than the trucks but not enough to be worth swapping it out. The aftermarket FAST etc. flow really well but are expense! You can upgrade to a TBSS LS2 90mm TB truck intake or an LS2 90mm as well.
The new L92 and L76/LS3 intakes will only fit the L92/LS3 square intake ports and won't fit the Gen III heads.
Also the DBW intakes are alittle different than the cable ones as well with the PCV locations.

11)Heads There are lots of choices now. From ported to stock. Stockers: The 317 stock 6.0L heads are based on the LS6 243 and flow pretty good. The 799 heads are basically 243. The L92 head will only fit a 4'' bore motor and will only work with L92/LS3 intake because of the different intake ports. YOu can add 243 to a 5.3l but it will increase CR as well. Then newer 5.3l actually come with 243 heads now.

12)Oil Pans There are several stock pans to choice from for your application. LSx oil pans pictures and dimensions.

13)Transmissions The Gen III/IV engine share the same SBC trans patterns as the early V8. So any SBC TH350/400/700r4 or Gen I 4l60 and 4l80 trans will bolt right up. You just need to correct flex plate and spacers for the earlier SBC trans. A spacer supports the torque converter nose. AND YES THAT'S THE WAY IT GOES!!! Some have even not even used the spacer. But, like i said it's to support the converter center.
TECH: Gen III/IV "LS motor" to Auto Trans

The Gen III converters for the 4l60 have a large center section than the Gen I and hence the dish. The spacers on the crank themselves are for the 4l80's with the 6.0ls behind them with flat flex plates.

4l80 converter Note the middle used with flat flexplate and spacer on the crank

4l60 Gen I/ 4.3L smaller center hub

4l60/65/70 Note the larger center hub for the dished flex plate!

There is a cheaper option for just a bushing that rides on the crank. A vendor here sales it for $20 search in the vendor setion for it.

Spacer from GM
GM PART # 12563532
CATEGORY: Engine Flywheel
GM LIST: $52.86

GM PART # 12563533
GM LIST: $6.86 each

The later model 2007 trucks using the E38/E67 ECM's use a separate TCM for all transmissions. So you will need the TCM for the 4l65/70 and the 4l80 as well. GM did this because they need the new ECM to control things like VVT and AFM and the transmission controls really limit the computing power so they separated them.

The new 6l80/90 will work, the TCM is internal to these, but the limiting factor with these is they require a 58x relutor wheel and new E38/E67 ECM controller. So these are only options for the Gen IV's now. Till some one makes a standalone for the TCM inside the trans.



The Gm engine Gen IV Vortec L92 6.2L /L76 6.0L and LS2/3/7. The basic difference's of the new motors are the placement of the knock sensors on the side of the block, a 4x cam sensor mounted in the front of the cam now, some have VVT, AFM, and a 58x reluctor wheel (crank trigger). These engines are the same as the Gen III save for these changes and most parts inter change from both family's.

EGR Block off plate
GM PART # 12558346
CATEGORY: Engine Fuel Intake Manifold
GM LIST: $22.03
OUR PRICE: $13.06

INtake Brake nipple adapter
GM PART # 12559760
GM LIST: $5.52
OUR PRICE: $3.28

That's just half of the info I have found, and will try to answer your questions! Anything to help!


· Registered
5,256 Posts
Discussion Starter · #2 ·

Blue connector
1 Ground BLK/WHT
2 Ignition LT GREEN (to crank position sensor)
3 Inj 3 PKN/BLK
4 Inj 2 LT GRN/BLK
11 KS Signal LT BLU
12 CKP DK BLU/WHT (to crank pos. sensor)
13 Req torque ORG/BLK (to electronic brake control module)
14 serial data ORG/BLK (to throttle actuator control module, fly by wire throttle)
15 serial data DK BLU/WHT (to throttle actuator control module, fly by wire throttle)
17 range b DK BLU (to transmission)
18 range c RED (to transmission)
19 ignition PNK (to fuse center)
20 B+ ORG/BLK (to fuse center, constant 20A fuse, ECMB fuse)
21 Ref low YEL (crank pos. sensor)
23 sens gnd PPL (EGR valve)
30 Coolant level LT GRN (on radiator)
33 BRK SW PPL (to black 14 pin connector then brake switch in car)
36 Inj 1 BLK/WHT
37 Inj 6 YEL/BLK
38 Lift Dive sig PNK/WHT (to suspension control module)
40 Ground BLK/WHT
41 Ground BLK (to transmission fluid temp sensor)
43 inj 7 RED/BLK
44 inj 4 LT BLU/BLK
45 +5V GRY (Fuel tank pressure sensor)
46 +5V GRY (TPS)
47 +5V GRY (MAP)
48 +5V GRY (EGR)
51 KS Signal
53 sens gnd (?)
54 sens gnd (?)
55 EGR input
56 Fuel Comp Sig (?)
57 B+ ORG (to fuse center, constant 20A fuse, ECMB fuse)
58 CLS 2 Data DK GRN (to OBD II diagnostic port pin 2)
59 CLS 2 Data YEL (to BCM fuel enable signal, serial data, VATS must be deleted in truck computers.)
60 sens gnd (?)
61 Ref low (?)
63 sens gnd (?)
65 HO2S HI
66 HO2S HI
68 HO2S HI
69 HO2S HI
70 Oil Level BRN (to oil switch in pan)
73 CMP BRN/RED or BRN/WHT (to cam pos sensor)
74 ECT sig YEL (coolant temp signal, to sender in head)
75 Ignition PNK (to fuse center)
76 inj 5 BLK/WHT
77 inj 8 DK BLU/WHT
79 3-2 SS except 6.0L BRN or White
80 Sens rtn

RED connector

1 Ground BLK/WHT
2 TCC PWM BRN (to trans)
5 Delivered Torque TAN/BLK (to electronic brake control module)
6 PC SOL HI RED/BLK (to trans)
7 EGR Control RED
8 PC Sol Lo LT BLU/WHT (to trans)
9 Fuel Pump DK GRN/WHT (+12V power output for fuel pump relay to fuse center)
10 RPM out WHT (tach output 4cyl signal to black 14 pin connector)
11 Recirc Sw DK BLU (to 2 pin connector on passenger side of harness)
13 Cruise Eng LT BLU/BLK (to black 14 pin connector)
15 Gen L BRN
16 4WD Low GRY/BLK
20 VSS Lo LT GRN/BLK (to VSS on side of trans)
21 VSS High PPL/WHT (to VSS on side of trans)
24 TP Sig DK BLU (to TPS sensor)
25 IAT SIG TAN (to mass air flow temp sensor)
26 Ign Ctrl PPL/WHT (coil )
27 Ign Ctrl RED or RED/WHT (coil )
28 Ign Ctrl LT BLU/WHT (coil )
29 Ign Ctrl DK GRN/WHT (coil )
33 Recirc Door DK GRN
34 Evap Can DK GRN/WHT (to solenoid on top of intake)
39 Ign Feed RED (cam pos sensor)
42 TCC SOL TAN/BLK except 6.0L (to trans)
45 EVAP Vent WHT (pin C of blue 12 pin plug)
46 MIL Ctrl BRN/WHT (to black 14 pin connector chk engine light)
47 2-3 SS YEL/BLK
48 1-2 SS LT GRN
49 VSS Out YEL/BLK (pin E of blue 12 pin connector)
50 VSS Out DK GRN/WHT (to black 14 pin connector)
51 TFT Sens Sig YEL/BLK (to trans fluid temp)
52 Gen F GRY (2000 only)
54 Fuel Lev PPL (to pin K of blue 12 pin connector)
55 CYC SW in DK GRN (A/C system)
60 REF Low BRN (to ign coils)
61 REF Low BRN/WHT (to ign coils)
62 PRND C GRY (to trans)
63 TRANS RNG A PNK (to trans)
64 Fuel SIG CTRL DK GRN (pin D of 12 pin blue conector, to fuel tank pressure sensor)
66 IGN CTRL PPL/WHT (coil )
67 IGN CTRL RED/WHT (coil )
68 IGN CTRL DK GRN (coil )
69 IGN CTRL LT BLU (coil )
80 ORG/BLK (pin G of 12 pin blue connector)

Black 14 pin connector. Not labled a-n, just identify order by wire color/placement

A blu/blk pin 13 cruise engage Depends
B wht Power steering pump pressure sensor No
C pnk canister evap vent Depends
D grn pin 50 VSS out Depends
E ppl pin 33 TCC Break switch If using 4l60e/ 80e yes
F brn/wht MIL control Yes
G Grn pin 58 serial data Yes
H tan/wht oil pressure Depends
I wht pin 10 Tachometer Depends
J brn Power steering pump pressure sensor No
K yel VATS No unless using BCM
L brn 4wd low No
M grn A/C recirc. No
N grn/blk to fuse center Me no, but you ?????????

Blue 12 pin plug

C Gry pin 45 evap vent Depends
D grn pin 64 fuel signal control Depends
E yel/blk pin 49 VSS out Depends
F wht pin 45 EVAP vent Depends
G orng/blk Pin 80 Blue connector No idea what it does??????????????
J blk pin 53 Blue ????????????????????????
K ppl pin 54 Fuel level Depends

2 Pin black connector is fo 4WD low range Not used

Large Black plug for fuse box. Not labled just follow diagram to find wire

Pnk Injection 2&4 Yes
blk ground Yes
pnk coils odd Yes
pnk ignition 1 Yes
ppl Starter Depends
yel PRND switch No
pnk Injection 1&3 Yes
pnk injection 5&7 Yes
ppl/wht PRND No
grn PRND No
pnk PRND No
Orng Battery Yes
pnk Front o2 Yes
pnk Rear o2 Depends
dk grn/wht Fuel pump relay Yes
pnk evap purge Depends
pnk injectors 6&8 Yes
blk Ground Yes
pnk coils even Yes
blk/wht ground Yes
LT Blue A/C Depends
pnk MAF Yes
drk blu A/C recirc. No
Grn A/C compressor Depends
LT grn PRND No
grn/blk to blk connector No/Depends
pnk evap vent Depends
pnk Ignition 2 pin 75 Yes

· Registered
1,080 Posts
2)VSS The computer needs a Vehical speed sensor (VSS) signal for shifting the 4L60E and get the motor to idle right. If running a manual trans you don't need to worry about it.
Wouldn't this refer to the pk/n sw and not the VSS?

Good info!

· Registered
5,256 Posts
Discussion Starter · #4 · (Edited)
Basically just using that as an example with out to much detail. Actually I have heard of people using the adavnced adapters VSS that goes between the transfer case and trans and having problems when being in four low and idle and cawling cause of the gear reduction and not in park.

· Registered
13 Posts
The pinouts for the computer change depending on what year LSX motor it is, and fbody and vette are way different than the pickups...just fyi for those looking into such a swap.

· IH/Rover Moderator
20,192 Posts
binderbound said:
thats some good info!

Hmmm, so this is what real tech looks like:D
Kind of a nice break from all the Monty Hall type posts!


· Fabster
2,107 Posts
I just picked up a LQ9 off ebay. Its from an 02 Escalade and came with the
4L60E. THe motor is rated at 345hp and 380tq.

You did a nice wright up. Have you got the rig running yet? If so how does it feel? Does it make the scout get with it?

· Registered
5,256 Posts
Discussion Starter · #13 ·
ChiScouter said:
Your a good man Bo, thanks for all the backchannel help

any pics of your motormounts?
Pictures of the Mock up stage so no bashing on the shitty stuff it will get fixed! I got everything apart and have may tub off to replace the entire floor and powder coat frame and line-x tub.


· Registered
5,256 Posts
Discussion Starter · #14 ·
Munchies said:
now if I could only find a 6.0 gen III for a bit less than my life savings
Easiest thing to do is buy a well used 2000 and up 5.3 complete. I paid 500 bucks for mine complete with everything computer harness and air filter and rebuild and run it or find a longblock 6.0L to swap for the 5.3. I bought a 6.0L longblock on e-bay for 600 bucks but I am building a stroker anyway so it will be rebuilt to a 408CI.

· Registered
6,155 Posts
Bo185 said:
Easiest thing to do is buy a well used 2000 and up 5.3 complete. I paid 500 bucks for mine complete with everything computer harness and air filter and rebuild and run it or find a longblock 6.0L to swap for the 5.3. I bought a 6.0L longblock on e-bay for 600 bucks but I am building a stroker anyway so it will be rebuilt to a 408CI.
Where the heck are you finding new engines for 500 $ ???:confused:
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