bought a 6.0 with 4l80e. now i have questions..

[Lookin4the1]

I found a great deal (or so i thought) in buying a 6.0 with 4l80e still attached. around 100k miles. i knew i would run into issue because the wiring harness was hacked and no computer. Sadly, i didnt know 2007 was a weird year and it could have one of two ECM or PCM etc.

What is the best way to identify what this truck originally had as far as a wiring harness and computer?

I plan to go through with i think current performance and have them build one from scratch with their computer, transmission controller, tac module and pedal but i need to know what to tell them in order to get it right. This harness is going to cost me more than the motor ha!

any help is appreciated, sorry if this is a widely discussed subject i didnt do much searching before.