I run solid mounts on my 70 Roadrunner as it seemed the over the counter rubber ones did not last and I was tired of changing them. Little more vibration but I don't really notice it.
I have been finding that the rubber used in alot of the parts any more is junk, I've had tie rod boots rot and split with in a few months of being replaced. I maintain a fleet of trucks and have found this to be an issue with the new stuff too not just our older muscle cars.
