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9 Posts
Discussion Starter · #1 ·
I thinking about getting rid of my crap box 700r4 and going sm465. My question is, how much shorter is a sm465 than a 700r4? Also, if I don't reuse my 241 SYE and go 465/205 is there going to be much of an overall lenth difference between my previous setup of 700/241SYE?

923 Posts
Find a sm465 that has a np208 behind it. Could be wrong but I think your 241 will bolt in place without any mods.

3,006 Posts
all the factory 700r's have a 27 spline output. the 465 was only available with a 10 or 32 spline in the 4wd configuration. you'll have to swap the input shaft in the t case to match the 465 32 spline. best bet is to find a 465/208 combo all ready together so you dont have to deal with the differences in 465 output shaft lengths.

1,367 Posts
well what is the rear output shaft spline count on a 205? Will the yoke I have on my 241's rear output work on the 205s rear output?

Both should be a 32 spline rear output. But be careful about using the SYE yoke on the 205. My SYE kit from JB Conversions uses a machined shorter yoke.

465/205 would be a stout combo, just expect to add a doubler or Lomax in order to have the same crawlability of the 700/241 combo.

Crawl Ratio
465/205 6.54 x 1.96 = 12.82
700/241 3.06 x 2.72 = 8.32 x 2 (torque mutiplication roughly) = 16.64

9 Posts
Discussion Starter · #9 ·
yeah I like the low range of the 241, but since i'm gonna have everything out of my truck, I think I might just go ahead and see about doing a 203/205 doubler

88 Posts
this is just a copy paste hope it helps



The automatic used in straight axle trucks are mostly of three types. The TH350 and TH400 three speeds and the super controversial 700R4 (early 4L60E)

My personal experiences with automatics is pretty straightforward. I started with a swapped in 700R4 and ran it fine for a year or so. It didn't like light wheeling though and decided to leak quite a bit. Boo to that! I dragged the truck to a transmission shop and the owner, an avid wheeler himself, helped me find a TH400/NP205 combo and put it in. I wouldn't go back.

Anyway here's a rundown of details.


The TH350. A basic, common, three speed.

Introduced in 1969, apparently as a successor to the powerglide

The TH350 is a fairly strong transmission, and from who I have talked to of off road message boards, holds up well in light and medium duty use.

In an unusual balance, the TH350 is fairly short for it's strength at 21.75" with no adapter.

The TH305 weighs in at about 120 pounds. Easily chuckable.

The TH350 pan is shaped like a square with the corner lopped off. It is held on with 13 bolts.

The TH350 case is cast aluminum

The TH350 is geared as follows: 1st - 2.52 2nd - 1.52 3rd - 1.00

The TH350 later was remodeled to the TH350-C, which uses an electronic lockup converter. It can be identified by an electronic plug on it's left side.

As a general rule, the larger the engine your TH350 was behind, the stronger it will be built. Upgrading the weaker versions is generally cheap and easy.


The TH400. A monster of a three speed.

The TH400 is a strong transmission, and is what most GM wheelers aspire to run when they want to stay basic and automatic. The TH400 is said to suck the most power from your engine compared to other automatics. They are easily serviceable, and can be built like few others.

The TH400 measures 24.37" long

The TH400 weighs in at about 135 pounds. Amazing huh?

The TH400 pan is shaped like a mutated Texas. It is held on with 13 bolts.

The TH400 case is cast aluminum and fairly smooth.

The TH400 is geared like this: 1st - 2.48 2nd - 1.48 3rd - 1.00

The TH400 is rated at 451 foot pounds of input torque


700R4. Love/Hate/Loathe

The 700R4 is a sticking point. Some love it for it's low first gear and overdrive. Some hate it for it's weaknesses and apparent love of exploding.

The 700R4 measures 23.40" long

The 700R4 weighs in at about 155 pounds.

The 700R4 pan is a square shape. It is held on with 16 bolts.

The 700R4 case is cast aluminum.

The 700R4 is geared: 1st - 3.06 2nd - 1.63 3rd - 1.00 4th - 0.70

Introduced in 1982, the early 700R4 had noticeable bugs, but by the late 80's, it had been reworked to negate these.

The earlier 700R4 can be upgraded with later stock parts, and all 700R4 transmissions can be greatly upgraded with aftermarket parts.

The 700R4 was renamed 4L60E in 1991.

Many 700R4's used in trucks have a thicker K case, as opposed to those 700R4s used in cars.

The 700R4 has 1/4" pipe fittings on the passenger side for running a transmission cooler. USE IT!

My super cool transmission shop man says: Every drop of 10 degrees adds 25K miles to it's life.


I don't have much experience with manual transmissions. Frankly, I'm a little sissy girl who can't drive stick. All I have is info.... poor me....


TH465. Hail to the king baby.

The SM465 is a heavy duty compound low manual used from 1968 to 1991

All gears in the SM465 are except reverse and first are synchronized

The SM465 has a case length of 12" and a case height of 18"

The case is cat iron and ribbed both horizontally and vertically

The SM465 is geared: 1st - 6.55 2nd - 3.58 3rd - 1.70 4th - 1.00

The SM465 weighs in at 175 pounds. HEAVY!

The SM465 has PTO ports on both sides

The early SM465 4WD output shaft was 10 spline and generally regarded as weaker than the later 32 spline version introduced in 1980

The SM465 has a top cover made of cast iron. Right on!

The Others

There are quite a few obscure manuals used in GM trucks from around 1969 to 1986.

These include:






They seem to be fairly rare though, so usually, when it's a stick, it's an SM465.


An Old Argument

An old argument - Which is better, automatic or manual? I've gathered a few of the points for and against both.

Clutch can burn out
Shock loads to drivetrain if clutch slips
Loss of momentum in low traction areas
Extra work to operate


On road driveability
Faster on easier trails
One less pedal to deal with
No stick to manipulate
Torque converter gearing multiplication
No loss of momentum during gear shifts in loose terrain

Weaker overall
Needs external cooling system
Less compression baking
Generates more heat
Possibly less reliable
Can't be run on it's side long
Hard to brake in low range


More specific gear selection
Stronger overall
No need for cooling
Compound low gear in some models
Maximizes low power output of smaller engines
Push starting
Easy roll back
Compression braking on downhill
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