Heavy vibrations at highway speed, possible diff?

Hello all am new to the forum and need help! So I just purchased a 99 SR5 4wd and have been trying to chase down this heavy vibration and noise from the rear. The noise is constant while on the gas and The vibration happens bad at 60+ and goes right away when I let off the gas, I found play in the u joints on the rear shaft so I replaced all of them and balanced the shaft and it did nothing I also drained the rear diff and put new fluid in to no avail.. the rear wheel bearings seem to be in good shape witch is all but leading me to a bad diff just need some input on what to do anything would be much appreciated

 

A little help, maybe? Similar problem. My recently acquired '00 2x4 4runner v6 auto with 240k miles has developed a new vibration issue. at low speed, under 30, it almost feels like a dead miss, smooths out between 30 and 55 or so, then comes back worse between 55 and up, as accelerating. But anytime its vibrating, if i let off the gas it stops. And its in the seat, not the steering wheel (so no front end suspension/tire prob, I think) and not in the brake pedal (so no brake probs either). No clunk when shifting into drive from park, but a bit of one when shifting from drive to reverse. The check engine light has been on for years (evap cannister, yeah, I know, on my list to get fixed, lol), but when this is happening the ck engine light starts flashing on and off. I helped maintain the vehicle for the last 10 yrs, as in offered advice when probs cropped up, occasionally drove truck to help diagnose probs, and took to shop for probs when requested. I don't know that the rear end lube level was ever checked (at least I never specifically told the shop to do it, may have been ck'd as some regular inspection). Getting codes pulled this afternoon. Looking for options, opinions and best guesses. I'm betting drive shaft or rear end.