351, 281, 302, Moped, Chainsaw...anything really. No matter what you put solid mounts in you are going to feel 100% of the vibration. They are designed to remove all of the slack in the drivetrain when under a heavy load or WOT, but unless you have a 100% track car, I'd go poly. You can always go solid, just make sure that you buy a good set of tools and some lock-tite for when you have to re-tighten everything on your car every few months.... :nonono: