all upsides and downsides of LS1 vs. LT1 are basically the same minus the motor mounts, and fuel pump(but if your putting a high hp motor in your truck why wouldnt you upgrade?)...both require a/c relocation, both require custom wiring, both require electric fans, and both require a new exhaust, and all are solved the same way(vette acc on an lt1 to relocate.....vette acc on ls1 to relocate, etc). LS1 can be put in anything for a lot cheaper and easier than buyin a whole new vehicle, going through salesmen, signing bank loans, and dealership papers, financing papers, etc., blah blah blah.