im running 39.5 iroks. I've got 30 spline longs and his hub gears, tg's trunnion eliminator and stock dual transfers. 4.7s in the rear case would be nice. but i havent broke anything yet. i dont drive like a retard either tho...
edit:
I went from 37s to the 39.5s as well. if you plan on driving it on the street then stick with the 37s. I've about decided to make mine a trailer only rig.