I just bought a 6.0l, a 4l80e and a computer to run it all. The engine is a 2001 and came out of a 4X4 suburban. The tranny is from a 2001 one-ton truck that is 2 wheel drive. The greaseball at Garraway's Auto Parts in Spanaway, WA who sold me all of this said that everything would work together. (Side note: I generally do not call people names, but the guy I have been working with has certainly earned it. Message me if you want details) So far the engine and tranny should work. The computer, however, is from a 2001 half-ton with a 5.3 and is 4-wheel drive. I'm going to assume that this computer will not control the engine or tranny. From this point on, I'm assuming that I need a new ECM.

Do I need to get a 4X4 or 4X2 wiring harness for this? I would assume 4X2 because this is going into a 2-wheel drive truck. I would also assume that GM doesn't have any difference in the physical engines-- it should all be in the computer, right? Therefore, there should be no wiring differences between a 4- and 2-wheel drive engine, or at least I assume.

I also bought accessories. The power steering pump and the starter are from a 6.0. I would assume that there is no difference between the accessory layout of chevy trucks. Then again, I used to assume that my mother had something dangling in the breeze. I was wrong. The alternator is from an '02 tahoe with a 5.3. With this work with my 6.0?

Also, does anyone know the fuel pressure I need, if this application requires a return line or if I will need a regulator off-hand?

If someone knows of a thread where I can find this info, please tell me. I have searched for all of these questions, I just haven't found answers. I at least attempted my own research. Thank you guys for any help that you give. It is greatly appreciated. Sorry about the length of this. I tend to ramble, just like in this sentence. I mean, look at how much more you have to read that has absolutely nothing to do with my questions. Anyhoo...