I beefed up my 10bolt with Chromoly Strange axles, all new bearings and seals. stuffed it with Yukon 4:10gears and loc rite locker in the back. I am only running 33s right now and may go to 35s but I would not go any taller than that with a 10bolt. I dont wheel hard or often so my stuff will hold up for awhile. IF you hammer the hell outa your rig, you may be go thru the 10bolts and if you breaking expense parts, its not worth it. If I were to run 37s and up, id go 14ff for sure.