83 gmc jimmy sierra classic

[Jerry Waller]

I have a 1983 gmc jimmy with a 12 in lift sittin on a set Of 38s . I have a 350 with a 700r4 automatic transmission in it. The problem is my transmission isn’t holding with the tires and lift kit. Ive been think about doing a manual transmission conversion on it but not exactly sure. What transmission or upgrades should i do so that my truck will drive and shift properly.

 

[Grit dog]

What gears and how fast do you want to go?
If it was mine I’d drop a built turbo 400 in it for ease of install, cost, bulletproof reliability and drive-ability.
Manual transmissions are great but they suck compared to autos in most off road conditions IMO.

 

[ctandc]

Yeah - before you blame the 700 - what gears are in it? 3.08? 3.55? With 38's I'd want AT LEAST 4.56 gears.

 

[Grit dog]

4.10s, no OD gear and real 35s, you're at about 2800rpms at 70mph. 38s could easily support 4.56s and still drive reasonably well on the highway.

Especially if you've "only" got a stock 80's 350 pushing the whole thing.