You're prolly looking at the same mods for 37's as you would be for 35's or even 33's if you want to do it right. 33's you can get away with not putting in a SYE or changing out the gears, but eventually you'll want to. The stock axle will handle the 33's if you're not on rocks and don't put a locker in...bigger and chances of breakage keep going up.

97tj, Shaved Ford 9 rear, 4:10's, New 35x12.5 BFG KM2's to test!, Warn x8000i, ARB's, Quick Disco's, Hand Throttle, & it's my DD. smile