In 10 years with a 1981 CJ5, 4 years with a 2000 TJ and almost 5 years with my current 1999 TJ, nothing yet. But, somehow I did break the D35 carrier in half in my 2000 TJ while driving it on the street {ehm}. Thankfully it was still under warranty at the time {hihi}.
KNOCK ON WOOD
Chuck