Curious on your thoughts as far as what this could be.
I get a vibration when I hit 25 mph in my truck. The vibes go away completely between 35 and 40 mph. It definitely feels like its coming from the back.
I checked the driveline, no obvious weights missing, ujoints seem to be tight. There is some movement from the carrier bearing, but it is very minimal, and seems to be just the rubber flexing. I haven't pulled the driveshaft, and it is still indexed correctly. Strangely, it seems as if this happened over night. I haven't checked the wheels out closely, but they shouldn't be out of balance at all.