I swapped my 5.3 for a LS1 in my 99 GMC Sierra. I used the truck PCM and 1st used the LS1 intake. I swapped the LS1 intake back to the truck intake, more lowend torque.

The donor vehicle was a 99 TA, suppose to have 305 hp at the fly wheel.

My last dyno, with stock internals, was 250 rwhp and 296 lb/ft of torque. I am having a problem with 8* of false knock so I know there is more power to be gained.

I recommend this swap, it's what should come in these trucks from the factory.

ts99