ECM in engine with manual transmission vs automatic transmission

[JulianGrives]

I'm currently researching engine swapping for my 95 Chevy. It originally had the 4.3L V6 with the 5-speed manual. I want to swap it with a 5.7L V8. I already know that it will bolt to the same transmission, but I'm looking to pull the 5.7 out of a junkyard (out of a 1994-95 to be exact) and I don't know if ECM is different depending on the transmission. I want to know if it would be ok to pull the 5.7 out of a truck with an automatic transmission, or if I have to find a 5.7 already mated with the manual transmission, then pull it and swap the ECM in my truck when the engine goes in.

 

[someotherguy]

The 94-95 truck with automatic will have a PCM since it controls the transmission as well. You won't be able to use that PCM with your manual trans.

You *might* be able to use your 4.3 ECM with the 5.7 providing you get the proper chip for it, but this is something I've never done so I could be completely wrong. I haven't swapped any 4.3 trucks to a 5.7, ever. I'm sure there's a few people here on the forum though that have and can advise further.

Richard

 

[FrankieD61]

I'm currently researching engine swapping for my 95 Chevy. It originally had the 4.3L V6 with the 5-speed manual. I want to swap it with a 5.7L V8. I already know that it will bolt to the same transmission, but I'm looking to pull the 5.7 out of a junkyard (out of a 1994-95 to be exact) and I don't know if ECM is different depending on the transmission. I want to know if it would be ok to pull the 5.7 out of a truck with an automatic transmission, or if I have to find a 5.7 already mated with the manual transmission, then pull it and swap the ECM in my truck when the engine goes in.

Skim through this:

Thread '4.3 TBI to 350 TBI swap' https://www.gmt400.com/threads/4-3-tbi-to-350-tbi-swap.54668/

That was my post for something similar you are doing.