I have a 93 Bronco with an 8.8 differential and I need to know if the ring gear backlash is adjustable?

 

Yep, but you have to take it apart to do so and when there is play there must be some worn parts. It just doesn't loose it's adjustment for no reason. If you choose to reset the BL then you need to confirm a good wear pattern as well to insure things will run correctly. You may also develope a whine from the rear if you do this. That will be form the worn gears getting moved from there worn position.