Just Another Driveline Vibration...

Hi all, 2010 ACLB 4x4 with 42,000 miles. 265/70/17 Toyo Open country A/T III's with about 10k on them. The only lift I have is the 1" you get when swapping for 3rd gen OR suspension. All vibrations can be felt in the pedals and the footrest where you put your left foot and nothing in the steering wheel. I notice it when under acceleration load from 20-30mph. Here it is very slight. just a couple random pulses then gone. Noticeable again around 50-60 mph but here it is a constant wave of pulses, about half a second pulse the a half second break then on and on, also still on the faint side. The most noticeable is at 70-72 mph. a constant vibration. When you go up a click on the cruise it is almost gone! All the way from 73-80 mph it acts the same as from 50-60mphNo matter what speed when you let of the gas it goes away. It started off with just the 50-60mph symptom but it has developed over a couple months. Unfortunately I do not have grease fittings on my rear driveshaft because of the TSB for U-joint strength or whatever it was. I haven't yet pulled the rear driveshaft to test in 4 hi because I don't think it can yield worthwhile results because of the vibration being at such a high speed. Seems like a U joint/Carrier bearing thing but with 42,000 that seems to soon.

Apologies for the paragraph, just wanted to give all the info I had.

Thanks all for the help!