Sometimes it's the simplest of things, your driveline "vibration" sounds just like the "shop truck" I bought off a bunch of ASE Certified mechanics who did an engine swap/torque converter swap and could never figure out the cause of the slight driveline vibration, so they "dumped" the truck on me, after 5 minutes of ownership, it was "cured"....firing order, 2 cylinders crossed wires, 4 ASE mechanics and a month of on and off troubleshooting, they over looked the obvious....so rule out the simple things before you go tearing stuff apart