I'd go with about every 60K miles or so. All diffs should use gear oil, I think it's the 85w90 stuff - but check. If you have a Dana 300, it also uses the same.
'82 Scrambler - NV4500/4.5" lift/33" Toyo MTs/4.0/twin stick, and my windshield washers work! Full 1/2 cab Cage
2004 Grand Limited 4.7 HO - OH Boy!
2010 Grand Laredo 5.7 Hemi - SICK - work vehicle -gone - replaced by an 08 Tahoe - nice ride.
"Both my Doberman and my Jeep can accurately be described as 'black and rust.'"
"I got a fever . . . and the only prescription is more cowbell"