I just moved from the phoenix area to up on our Rim. From about 1800 ft elevation to about 7000 ft. I pulled a small mobile home that I am living in up some very steep grades for long duration. I believe that the trailer was a little over 4000 pounds. I know that it really made the Jeep squat in the rear. I have a dana 35 3:73 ratio with 31 inch tires, Automatic and 4.0 engine. I didn't know if the dana 35 would blow or what, but it handled it just fine with no failure. As for power, well it really struggled on them steep long mountainous roads. At times I could only get about 10 MPH out of it, but I made it there safe. The engine temperature went up to about 240 on the long grade pulls, it normally runs about 210.
These Jeeps just are not very good for towing. I guess that is why they rate them for 2000 pounds max towing.