hi
im guessing you have a full-size? you'll be fine w/ 33's. on my old 3/4 ton i ran 35's with the stock 700r4. i did change the ring and pinions to 4.10:1 to get a little lower gearing. i had no problems with the tranny, though, and i beat the crap out of that truck.
Heat is the number one killer of trannies. Upgrading ring and pinion gears will keep the tranny and engine in the proper power band and reduce the amount of heat generated, plus pick up some lost performance. However to make the tranny survive, I would recommend an auxiliary tranny cooler. The tranny will generate tons of heat while 4wheeling. Proper ring and pinions will only reduce that a little, the auxilary tranny cooler will help the most.





