driveshaft bent???

I'll try to get this topic back into perspective, to see if we can possibly help Dave out here.
A few things I would look into, would be "U" joint wear, driveshaft should have a balance plate spot welded to it, and leaf spring bushings. All of these will cause vibration, and make it look like the driveshaft is the culprit.
Start with the basics Dave, work from there.
Good luck, keep us updated.
Hope this helps.