I have a 2003 1500 Suburban, 5.3l, 4L60E 4x4, and 3:73 axles. Its max towing is 7,200lbs. If I go to 4:10 axles I can get to 8,100lbs. Also swapping in a 4L80 in place of a 4L60 is not a straight swap if I remember correctly (different lengths, no speed sensor). At the weights you a planning to...