If my car makes a clacking noise while driving in reverse what can it be? on 1997 Volkswagen Jetta

While backing up I here a clacking noise and had it checked up by a few mechanics and they say its my axle. Can it be my axle or transmission going out?

Asked by for the 1997 Volkswagen Jetta
Probably not axle!!!!!!!!! There are mechanics and then there are....well, people who don't have a clue about alien technology, i.e. Jetta. If it is a standard trans, they inherently make a whining noise in reverse, however, whining noise accompanied by a clacking noise, or a thud-thud-thud, is broken/damaged reverse gear in transmission. If it is automatic trans, it very well could be axles, yeah right, if you are doing a hundred in reverse turning left or right???????? Lol. Sorry, I get frustrated easy.
Can I fix the tran.. My self four that reverse