My question: Will there be any issue using a harness and/or ECU from an 07 2500 Sierra in a 99 1500? I know there will be issues with VATS and the DBW that the 2500 has but the 1500 doesnt. There is a tuner locally that can take out the VATS but I'm unsure about the DBW.

Backstory: A friend let an ex-felon "friend" use her vehicle (99 1500 truck) and it has not came back yet. She pressed what little charges she could (unauthorized use & joyriding) but has no legal recourse since she authorized use but did not have a contract of when the truck was to be returned. The guy has multiple warrants pending and claims it was left in a parking lot so he wouldn't get in trouble for outstanding warrants on top of the charges she filed. It would not surprise me one bit if he cut the harness to pieces, ran it hot, etc. All we can do is wait until a towing company send her a note saying they have it in their yard. I have everything above the heads from a 2007 2500 junkyard pull. Intake, sensors, harness, ECU, etc. The only thing I dont have is the TAC module and pedal assembly. Good time to go carbed I suppose