Running solid engine, poly trans. No complaints, vibration is a non issue when running poly suspention components with race springs and shock. Idle is cool with a cam, the fender shakes a little and when looking from the rear, the whole car rocks...just looks menacing .
There's no conversion -- it's just unbolting one type and bolting in the other. They even stopped using different mounts in the later years and went to all cars getting the convertible style. Guess that's why I missed what you were asking.
i love my energy engine and tranny mounts, the car is alot more responsive and snappy feeling, but my old mounts were all torn the difference is alot bigger. i'd recommend the poly mounts. the solid ones, if your pushing over 400hp, will actually hurt the engine a little bit because it can't filter out the vibrations and shocks the engine, which can cause premature failure on some already weak spots on a stock HO 5.0.