Talked to a Tech from Energy Suspension about the flat metal plate on the poly trans mounts for our cars(700r4). He said that the plate is to be installed as it helps support the bushing's interlock system. There are actually two types of poly used in the mount and the compressing of the plate to the end ears of the mount makes the interlock more effective in case of failure. As for vibrations in the driveline, he says that one of the most overlooked things is variances in our cars. Just because you replace a part does not mean it goes back to OEM status. Slight differences in height,structural flex in the uni-body,etc., can cause misalignment of driveline parts. He suggested for those who have vibrations, check for the correct amount of pinon angle and if the trans mount does increase the height, try shiming the crossmember.Poly mounts will give you more transmission of harmonics in any car, its the nature of the beast. Also when you install the mount,make sure the bolt that goes through the center of the crossmember to the mount is not touching the sides of the crossmember. This can also transmit sound. As I have discovered when replacing the entire suspension on my 85, using a combination of poly and high-durometer rubber mounts, you get a lot better handling but pay the price in ride harshness and more transmission of "road feel". But if I wanted a smooth ride, I would be driving a Caddy. The bottom line is that you have to try different things to solve problems like vibrations, and hope you figure it out. Badman