I replaced my motor and tranny mounts on my little red jeep yesterday... I used MORE (rubber control arm bushing?) motor mounts and an AutoZone rubber OEM type for the tranny.
I did the motor first, and when I fired it up to check for oil leaks, I noticed a bunch more vibration, especially at idle. I may just replace them again with stock and swap the MOREs onto the trail rig where vibes don't matter. They do appear 'bombproof' ecpecially when observed next to the bombed out stockers, and are servicible later on... I was hoping the tranny mount would help still things out, but it didn't.
I have no experience with poly mounts, but I'd expect it to be pretty buzzy.
The unique & $$$ Peugot 5 speed mount on my MJ failed/split horizontally through the rubber, so being cheep & industrious, I drilled a 1/2" hole on each side and thru-bolted it back together. It worked longer than the tranny did :dunno: and it didn't vibe any more than before.