Need serious GMC help - 6.2L Diesel to TH400/425

[tigger4x]

I am looking at a potential tow rig that has a 454 with a TH425 behind it. I want to put a diesel into it for the better milage, torque, and life span. I can get my hands on a 6.2L but it currently has an SM465 behind it, I think. I have heard quite a bit of pros and cons on the 6.2L, but it is a cheap buy and only has about 1,500 miles on a rebuild.

My question is : IF I buy this tow rig, will the 6.2L bolt up to the TH425 currrently in the tow rig If not, what componentry will be necessary Of course I would like to go as economical as possible.

Time is running out. Your help is greatly appreciated! BIG THANKS!!






And IF all goes well, I'll have a 454 and an SM465 for sale.

[larryboy]

i really don't see the point of what you want to do .
i thought you had a rig w/the 6.2(from your other posts),why take out a 454 and put in a 6.2??? have you driven a rig with the 6.2? i've got a lot of time with them and they are really terrible gutless slow underpowered not that fuel efficient clunkers.why not spend the $$ on some stuff for the 454? just my opinion .

[tigger4x]

Originally posted by larryboy
i really don't see the point of what you want to do .

Originally posted by Tigger4X
I want to put a diesel into it for the better milage, torque, and life span.

Originally posted by larryboy
have you driven a rig with the 6.2? i've got a lot of time with them and they are really terrible gutless slow underpowered not that fuel efficient clunkers.

I did get a chance to drive the 6.2 but it lacked top end with the SM465. The seller stated he gets about 25mpg which is hella better than the 454 does.

Originally posted by larryboy
why not spend the $$ on some stuff for the 454? just my opinion.

Spend more $$$ on what stuff And what kinda real world gains will I get for the $$$ spent I need longevity in both life span and traveled distance between fill ups.

[70~K5]

I don't think that he's getting 25mpg from that rig. Have him fill the tank and take it on a 100 plus mile drive and fill it up again and see what it gets. Also check the speedo/ odom. too.

[tigger4x]

Originally posted by 70~K5
I don't think that he's getting 25mpg from that rig. Have him fill the tank and take it on a 100 plus mile drive and fill it up again and see what it gets. Also check the speedo/ odom. too.

A couple other guys I have "talked" to have stated tey get about the same from their 6.2s. And AFAIK the speddo is accurate as well. I test drove it and it seemed good to go.

[larryboy]

if it lacked top end with a 465 why would the th425 help?

25 mpg? doubt it .

again i ask whats your point...better mileage? nope. better torque? nope. better longevity? maybe,just maybe.

is this a tow rig or a half ton short bed commuter??

if you want to tow the 454 is a much better choice than the 6.2.
towing with the 454 you can keep your foot out of it.with the 6.2 your foot is on the floor all the time.you would do good to see 9-12 mpg with the 6.2.

by stuff i mean a cam and fuel injection if the 454s torque isn't enough.

[smurfsdad]

I owned an 85 GMC crew cab with a 6.2 that had an ATS turbo on it. KEEP THE 454. Anybody that tells you they get 25 mpg with one flunked math in school.

[tigger4x]

Looks like I'll be sticking with the 454! Gotta work up the cash now.

Another one for you guys ... Howzabout an NV4500 instead of the TH425 I know I'll have the shifting to contend with, but with the 5.62:1 granny low and the 27% OD 5th gear, it sounds tempting. Whatcha say

[larryboy]

now that you have quit all that crazy talk , we can help .

nv4500 behind the 454 is an outstanding idea

[tigger4x]

Originally posted by larryboy
... nv4500 behind the 454 is an outstanding idea

Now the hunt begins for which donor to scavenge from.

Anybody have .02 on which rig(s) have a bolt up application.

:rubshandstogether: c'mooooonnn larryboy!! :throwsdicetoendoftable: