I put a 06 SS LQ9/4L80 in my 71 C30 dually I used the matching 6.0 wiring harness and had LT1 wiring redo it for the swap and since I didn't have the computer they sold me one from a 5.3 but had it recalibrated to the specs of my 6.0 I used everything else from the 2006 donor except the coils and coil rails they came from a 05 corvette, I
'm getting fuel it seems but it just will not turn over can I get a little help this is suppose to be my old but new repo truck.

 

Tony welcome to the site. Please take a look in this thread to get some idea's. https://www.performancetrucks.net/fo...-start-497351/

 

What year 4L80E? They used several different neutral safety switches.. I believe in 05 they changed the switch

 

Ok fully read it and was the tune set up properly? If he tuned it for pre-05 its tuned for a diff harness