Well, replaced the rear shocks with Bilstein HD on the back, and replaced the rubber mounts on top of the rear springs yesterday. Overall, not that difficult to do. I was fortunate enough to be able to use a coil spring compressor I had for my 66 Mustang to help removal, took about 3 hours for both sides. I used the thicker 19mm coil spring pads, and it made a big difference in height. Overall, I think the rear came up about 1.5 inches on each side. I know it will settle, but not bad for now. There is still something more to do for the rear, the left side sits a half to an inch lower than the right.

As for the vibration and driving, major improvement. If the vibration is still present, it is barely noticable. We'll see how it is after driving for a while, but I'm happy so far. Next step is replace the driveshaft support, I think it is wise to do so, and probably the rear diff mount.

But, I'm going to drive it for a while with just the new coil spring pads and shocks to see if the vibration stays away.

I just wanted to update the post with some positive results, my opinion for now is the coil spring pads made the difference. Not bad for a few bucks and three hours of labor.