I have a 2003 Av 2500 4x4 with 3.73 gears which is tow rated at 9,900 lbs. The same Av with 4.10 is rated at 11,900 lbs. Besides the different gear ratio, is there any difference between the two? I believe its old tag indicated the trailer hitch is a Class 4 rated at 12,000 lbs. I have pulled a 12,000 lb boat trailer without issue (11,000lbs on the trailer axles / 1,100 lbs tongue weight) to the scale, also 4,900 lbs on rear axle of Av which is rated at 5,500 lbs. I don?t want to temp fate, but before I replace the Av with a Pickup 2500 HD Diesel rated for 13,000 lbs I wish to know if there is a difference between the two Av 2500s (3.73 & @4.10) besides the gear ratio? Does the 4.10 have a higher weight rated hitch, bigger brakes, chassis? FWIW my Av 2500 sat level (no rear squat), steered fine, front axle weighed in around 3,800 lbs, pulled and braked the trailer very well ( I have a high end trailer with disc brakes). I live in a relatively flat area, no mountain or big hills so the Av 2500 power is more than adequate. Last question... is there anything I can do, aside from changing the gears to 4.10, which would increase the tow rating on my Av? Thanks