I jus bought a 99 Z71 and i jus had the tranny built and took out the 5.3 for a rebuilt ls1 with 5.3 heads and ls1 hot cam. Besides tune, what will i need to make it work? I have headers, ported tb, cai and a catback. Thanks for ur imput

 

It should be direct drop in. Only thing I can think of is that you need to relocate the alternator from the stock ls1 position to the truck position. I'm not sure if this requires drilling a hole(s) in the block or what. PM Regency, he'll know exactly what needs to be done.

 

Just drop it in! Use all your accessory brackets and accessories. IF your going to run the LS1 intake you will need to change the injector plugs for the LS1 style. and you will need to make a bracket to relocate the idler pulley thats on the alt. bracket to straight down under the alt. pulley