Try to find one from the same generation of XJ with the same transmission type and you will be fine.
If its same year and transmission, the only differences are the shift gate, bezel, and wiring (stock harness already has the 231 connector so just remove the 242 sub-harness and find the plug for the 231 further up)
Input gear changed on different generations and transmission types, so you would have to rebuild one that was older than 91, maybe if it had a different transmission too. Output shaft changed for 96-up so that would require a different driveshaft.
Other vehicles had different clocking patterns and other changes, so try to stay away from those