If I replace my 5.3 with a 6.0 will I have to change the pcm and wiring harness

 

Nope. Just get the same generation to keep it simple. Gen III engines have knock sensors in the valley and a cam sensor behind the intake manifold. Gen IV engines have knock sensors on the side of the block and a cam sensor in the front cover. There's a few other differences, but those two are the main ones when doing a swap.

 

Welcome Charlie to LS1tech!

Tell us more about your plans. Vehicle and what the new motor is or is from.

https://ls1tech.com/forums/generatio...g-threads.html