From what I understand so far is that I can put a 5.3l no matter the year as long as I use my intake and Injectors and so on. Is that true? And is it possible to use a 4.8l? I've just never seen a flex fuel 4.8lYou can put anything you want in there. More work. Stay with what you have. Code list in glove compartment and emissions sticker under hood some help. I hope someone else chimes in with details.