I have a 01 Chevy Ex cab short box Z71 and tow a 2000 lb (dry) 18 foot + dovetail trailer and a 1939 John Deere D weighing in at a little over 6000 lbs by itself. Tows it pretty well, but is very slow getting up to speed. Because of the soft springs on the truck, and farther back trailer axles than I wanted, I keep the load towards the back (keeping 10% tongue weight).
I specifically ordered the truck w/ 4.10's to get a max towing capabity of 9000 lbs. 33,000 miles and several loads and no issues. Hoping the tranny holds up (4l60e).