i found a little pdf thing online saying the 03 was rated at 10,300 for an ext, 4x4 short bed with 4.10 gears. 15,700 for a diesel, fifth wheel trailering, but it doesnt have a "max trailering package" since its a 2500hd, that was a pacakage on 06+ half tons. that package consisted of 4.10 gears, HO 6.0, 4l70 transmission, and a 14bolt rear end.
But that 6.0 is going to hate 12k pounds. even if the truck was capable i wouldnt do it, diesel is the only way to go if you are thinking of that much weight.
Last edited by bad2006z71; 04-26-2010 at 02:56 PM.