My lower shift boot is off and I can see my transmition and shifter bouncing. I looked up tranny mounts and summit racing has polycarbonate or something like that tranny mount but when I search rear transmition mounts it comes up as almost an almsot different looking part, I was wondering to fix the bouncing do I need to replace the (rear tranny mount) or the aftermarker summit tranny mount.

 

The poly mount looks a bit different than a stock style rubber mount. They both serve the same purpose and bolt up the same. The poly mount is stiffer and will probably never wear out. The downside to them is the possibility of drive-train vibrations tend to pass through the poly mount up into the car. A lot of people find that very annoying and switch back to a stock style rubber mount (myself included). The downside to the stock mount is that they tend to wear out quick. The rubber component of the mount can separate from the metal part and you are back to having a bouncing shifter. The good news is the stock style mounts are only a few bucks and easy to change out when/if it fails again.

 

greenyone nailed it, go with the rubber mount if you want as little vibration as possible. they're super cheap and takes like 10 minutes to change.