I am going tomorrow to get the motor. It's out of an 03 Sierra. It should be fly by wire. If it is, can I use that harness or do I need to use the one out of mine still. I'd prefer to use the new one if I can. I have a bunch of splice's due to the previous owner's swapping skills

 

just use yours... you know its in good working order.

but its easy to swap since your goin to have the engine out of the way
they should be the same harenss, you will know shortly.

 

use your existing harness.... if they will give you the -05 harness ...take it and sell it!

 

And just live with the splicing?