rocking engine

[nielsmobers]

Hey,

I have a rocking engine in my 1972 grandé 302cu , I've already replaced the vibration damper which took away have of the vibration. When I drive about 50mph the engine vibrates like this: rrrrRRRRRrrrrr rrrrrRRRRRrrrrr rrrrrrRRRRRrrrrrr rrrrrRRRRrrrr. I'm 100% sure it's the engine, could it be that they gave me the wrong damper, it's an universal damper for all ford small block engines. At first I was told that it had to be a damper from exactly the same engine and year as the car, but they gave me an universal damper. Does someone also have vibration problems with his/her car, I don't know what to look for, any information can help. This Saturday I'm going to Antwerp (Belgium) to a mustang day there I will also try to find some answers.
Thank in advanced

Niels