I used an ES insert for the front mount by the radiator mainly because it was $22 for the insert kit, and that front mont alone was like 60 or something. I tried using the inserts for the side mounts but didnt like the vibration, so I went to OEM for the sides and havent done the rear. The car responds sooooo much better with the 3 new mounts and only has slightly more vibration than stock due to the fact that the front mount is solid instead of gapped like OEM. I remember when I had all busted mounts, when I went from reverse to forward , I could hear the engine jumpin around, didn't like that at all. Maybe I will try some polyurethane filler in a caulkin tube for the rear mount, but as it is, doesn't seem like I need to mess with it. When I build this motor up I will replace the rear mount while the engine is out, much easier then.