I don't know EXACT differences but the blocks changed in the TJ's around 2001-2002 (I think). I know the XJ don't bolt up and Some bosses for bolting accessories were relocated. TJ's with the AC unit on passenger top side have different bosses than those with the AC on the drivers side like my 04.
I tried to match older accessory brackets to my 04 from an XJ with no success without mods.
~Todd~ 2004 X 4.0 5 speed---SOLD
4" Lift, 4.56's, 33" Duratracs on M/T Classics
RR SYE, Tatton CV, MML, BL, TT, Dynomax Exhaust
Hella Lighting: Driving, Fogs and H4 E-Codes
... and NEVER will be