yes they break i do a mod to the mount bracket that limits the travel and makes broken mounts a thing of the past its easy to do on mount there is a tab and a window that tab sits in just weld in half the window and tab will catch before the mount is fully extended mounts break from over extension of the mount .
I've gone through 2 sets.....and i'm on my 2nd tranny mount as well. All were solid rubber......
This seemed to stop the motor mounts from tearing... This is what I did.... I used a piece of Derin just to soften the blow. I positioned my tab on the outside at the time because I was going to make a torque strap for track use that would be installed on the inside. Never ended up doing that...but it should be positioned on the inside to reduce the moment-arm....
i will have to try that when i put a set of rubber back in. for right now to get the car back on the road i made some steel mounts at work. hopefully i will have it up and runing this weekend.