I'm swapping a 00 6.0 into my 03 Silverado. Going from a 4.8 t56 combo to the 6.0 with a 4l80e. The trans harness is cut from the t56 swap. Is it possible to swap the harness and pcm from the 2000 into my 2003? Going to drive by cable in the process. Or do I just find a uncut 03 harness?

 

Any insight at all guys? I have found information saying yes everything will work. Then more information saying no it won't.
Is there any benefit to going drive by cable? I assume the cable is nearly trouble free. Read something about better resolution with going speed density and using the cable. Anything to that? Thanks in advance for any insight.

 

You can NOT use a 99-02 engine harness in an 03 up truck and ViceVersa.


There is actually a few small differences in 99-00 Vs. the 01-02 engine harness for the charging system but it can be changed in the tune.

 

Thats good to know. Would the pcm be interchangeable?

 

99-02 interchangeable

03-07 classic interchangeable

Just need the correct operating system in there.

 

Last noob question. The harness is 99-02, 03-04, 05-07 classic correct? Im looking at a couple on ebay. Just dont want to buy the wrong harness. Starting to think it might be easier to just rewire the trans plugs.

 

I believe the engine harness is basically the same from 03-07 classic.

07 was the split year for production so GM calls it classic if it's GMT800

The tac module and pedal changed in 06 and is different from 03-05 model.