In 73 they redesigned the motor mounts for the V8 to where they are a captive rubber design. The only way they break is from the metal tearing apart, the rubber deteriorating, or from some other fluke. If you are changing from a 6 cylinder to a V8 you may have to change the mounts and where they are located in the subframe but in the 29 years of owning my 73 and less years with my other V8 nova's I have yet to break or bust a factory motor mount. I've seen my fair share though of 72 and older mounts breaking just due to how they are designed. I have though heard of people modifying the older stock ones to where they are harder to break apart but sometime's it is easier just to replace with new.Ironcross25 said:If you can get the whole mount off I would get poly mounts, you will be much happier and they will never go bad. Check summit racing they may have them. I put poly on my motor but the mount that bolt on the frame are all steel with no rubber. The 72 that I had was rubber and they were shot.