Could someone please tell me the difference between a "T" motor in an '05 Silverado and a "Z" motor in an '05 Avalance? They are both 5.3 and I don't think either has VVT or DOD. Is one Flexfuel? What are the mechanical differences that would affect tuning? I asking because I flashed one of my "T" motor experiments into a "Z" and it runs GREAT, just wondering about the details. Thanks!