The vibzzz are killin me!

I have this exact same problem. Car did this with the old 318 engine and is still there with a new 360 engine. I've also had the entire rear end apart, with the exception of the carrier and pinion bearings. Axles are new with new bearings. Im going to pull my driveshaft and have it balanced to see if it eliminates the problem. Im stumped as well!! I wish you luck and post up if you figure out what it may be.