Downshift Noise in rear end

[JKeyt]

I have a fairly loud "clunk" heard when auto trans downshifts....now occaisionally upshifting. Is it u-joints, suspension? Also have spark knock when coolant temp gets around 190...any suggestions (egr valve?)

Thanks
1989

[vetteboy86]

I have an 86 roadster that makes a clunk when downshifting the automatic rear end. It also makes this noise once in a while when shifting from park to reverse, or park to drive. Mostly in reverse. I have had new u-joints put on the half shafts, however my next course of action would be the joints on the driveshaft. If you could offer any information since you submitted this it would be greatly appreciated.