You should'nt have any problems towing that trailer. I use a '97, 2500 Sub, with the 350, 4.10 gears, and the 4L80E trans, no problem to tow that weight at all, you just keep the revs up, in the mountains.
All the 2500 Subs have the 4L80E trans, (untill very receantly).
The 10 bolt rear is only on the 1/2 ton models.
The 3/4 ton models use the 14 bolt, simi-float axle, not as good as the full floater, but still a very strong unit.
The 12 bolt axle, has been long gone.