Our 82 245T has a kind of weird problem. Under what I'd consider normal throttle application at reasonable rpm ranges (2000-2500 rpm) in 4th and Overdrive, the car has a noticeable driveline buzz, or shake. It's felt throughout the car, almost like it's got a bent wheel or something.
However it comes and goes with acceleration- if I coast, downshift to 3rd, engine brake, or simply apply less throttle, it doesn't vibrate.
I thought it was related to a squishy rear transmission mount, so I replaced that, and there was a slight improvement but the noise and vibration is still there.
I checked u-joints while I had it up in the air, and they're tight. They look dry, so maybe they need greasing? The entire shaft turns as one unit, no clunks or looseness at all that I can find.

Any ideas?
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Rob Bareiss, New London CT ::: '87 244DL/M47- 234K, '82 245T/M46-182K, '89 244DL/AW70- 212K Not too distant past: 86 244DL 215K, 87 244DL 239K, 88 744GLE 233K, 88 244GL 147K, 91 244 183K