Ok my dad has and 85 sierra 3/4 8 lug truck, and I gave him a complete 05 5.3L After his old
350 gave out, the stock tranny worked ok, well we want to the swap but what is need to make it work but would be easier to put a 60e behind, do we need to complete wiring harness? Its going to be his DD So it needs to be reliable, any advice
Is wanted thanks

 

There is a thread about a guy that swapped an ls engine into his box chevy.Might want to check into it