Along with the two engine mounts, they mount the engine and tranny unit to the body of the car. The rubber parts absorb the vibrations created by the engine. They also flex to compensate for the twisting generated by the torque of the engine. When the rubber wears out, they flex too much, rip or sag. In the case of the tranny mount, they can sag, causing the exhaust system to cluck against the tranny. You will only notice if it was bad to begin with. Another common problem is the shifter bushing. They serve to isolate the shifter quadrant from the tranny. If they go back the shifter will lift up and down and eventualy rub against the drive shaft. Those are a PITA to replace. They are located above the tranny but below the tranny tunnel. They would be easier to change if the tranny was slightly lowered during tranny mount replacement. Still the better part of a 2 hour job. Remember, you have a 26 year old car. You will sooner or later change or rebuild everything that is rubber or has rubber in it. When ever you get a chance to do multiple things at once, you should ignore the expense and do it. It will only cost you more later on if things have to be disassemble again to get at the bad parts. I have been restoring a low mileage car that sat since 86. It has been just as much work to get roadworthy as a high mileage neglected car. Everything needed to be gone thru, and I still can't get the clutch unstuck. I think I might as well drop the tranny and install a new clutch and resurface the flywheel.