Problem with 1988 rx7
 

i am having a problem with my rx7 everytime i shift from 2nd to third and on up it makes a loud clank sound that is hard to point out where it is it seems to be coming from the drive shaft my first thought was maybe the u joints were bad but i can't figure out what it may be it also causes the car to have a bad shimmy in the rear when i get above 55 but if i take the car out of gear and slightly push it back into a gear with the clutch in the shimmy stops so i can't get a fix on the problem any ideas or other questions would help out alot

First things first.

Punctuation. Sentences help alot. If you want people here to help you out, make it easy to read and understand your problem, ok?

Second, I doubt it's your u-joints. Sounds more like a transmission problem, maybe a bent shift fork or something, at least for the 2nd to 3rd gear change. You may have multiple problems, one stemming from the other.

Check your front differential mount. It's probably broken.

James