Here is some information on your solid mounts (Utility mounts). I am unsure why the others fit so poorly unless they have extra rubber cast on them (possible with repros). I would try grinding a bit off them until they fit? The solid mounts were designed for HD continuous use applications and may have more vibration potential.

https://www.stovebolt.com/ubbthread...s=motor+mount&Search=true#Post819727