1996 Jetta Vibrates in Reverse

I have a 1996 Jetta. It just recently started vibrating (badly) in reverse. It goes away immediately when I shift it into another gear. It is an automatic. Ideas?

Yeah i think it is automatic. Why do not you visit to some car mechanic.He will surely fix all issues.

I don't use mechanics. Every mechanic I've ever used has always found $3000+ more of things to fix. Things that "can't wait". Anywayyyyy. What are some possible problems that could be causing the vibrating? Keep in mind that it only does it in reverse (in any speed) and happened all of a sudden yesterday..