OK...I am looking at removing my 4.3 V6 out of my 1996 GMC 1500 Sierra
> (2WD). Motor is too weak for what I want to pull. I want to replace it
> with a 350 out of a comparable vehicle. I know the harness, ECU, and all
> accessories must all carry over from the donor truck...but what other things
> should I look out for? Are the tranny bellhousings the same? The front > springs?
>
> Has anyone attempted this and succeeded? I plan on keeping this truck until
> it rots away so I am not at all concerned with resale value. I plan on
> making additions like headers and dual exhaust, aluminum radiator, engine
> oil cooler, and beefy tires. I have already sourced a donor truck so now it
> is time to hit the homework really heavy.
> Any and all comments, pointers, tips, and pitfalls are welcome.
>
What year is the donor?
Tranny doesn't need a thing, unless you want to play with a different stall speed convertor more suitable for towing. Gary's made some recommendations on good ones in the past. Your motor mounts will work, just need to move them up to the other holes about 4 inches ahead of the current ones (on the frame). Springs would be a little softer, but not noticeably. I wouldn't bother changing them if you aren't going up to beefier brakes. I went from 8 to six in my blazer and it didn't make even an inch difference in ride height. Don't forget the radiator shroud from the donor, and the fuel pump relay is different between the six and
8, so get the stuff off the firewall too. Look at the rear end, while you are at it. The 6 cylinder units rarely had posi traction or even good limited slip units.