I'm having the same issue with my 65 Barracuda, can you give your $.02? Just started after the first 100mile road trip...Vibrates rather aggressively as soon as I start, in Park, can feel it humming and the floor shift housing vibrates. In gear, it actually is a bit LESS noticeable, but I can't tell if that's due to the noise of the exhaust. 318 with mild cam, and someone threw in an 8.25 rear end, at least I don't think it's stock.
