Has anyone else installed one of the Ultra rear main seals in their big block and have any trouble with it? I just finished pulling what was left of the one I put in a 400. The thing unraveled and then wadded up on one side of the crank. I followed the directions to the letter even bought a billet lower seal retainer, put the roll pin in as directed, and the thing failed in less then 20 mins of run time. It looks like to me that the thing just unraveled and then wadded up on the pin. going to replace it with a Viton one this time. Called Mancini where i bought it , and of course they said "never heard of that happening before", standard line . Just would like to hear if anyone else has had a problem. Have a happy turkey day.