Backup lights

[93xj97347]

Where is the best place to start when trying to figure out why the backup lights don't work besides the bulbs on a 93 xj with 4.0 and aw4

[4.3LXJ]

The neutral safety switch. Start there and work your way back

[NW99XJ]

Agreed. The NSS is the most likely culprit here.
Removing, and cleaning the Neutral Safety Switch is not all that hard of a procedure.
Here's a good write-up on whats all involved: http://www.xjtalk.com/showthread.php?t=1747
See for yourself if this is a project you'd be able to take on or not.
Hope this helps, Good luck!