My 1991 740 M46 has a nasty driveshaft vibration. It was much less with snows 185-65-15 vs 195-65-15 summers (now). It occurs around 60mph and will lessen or worsen
in and around there. It appears engine driving related, coasting with the clutch in is smooth but getting back on the gas will start it again.

The centre hanger bearing is good, the rubber support (about 4-5 yrs old)is fairly
soft compared to an old one I removed.

I'm wondering if even if the trans looses no oil can the output bearing (overdrive) be part of this and would a push and pull on the driveshaft axially indicate a problem bearing? Should this area have zero movement?

I'm looking to diagnosis the problem not keep replacing parts till the issue goes away.
cheers ian

"...I'm wondering if even if the trans looses no oil can the output bearing (overdrive) be part of this and would a push and pull on the driveshaft axially indicate a problem bearing? Should this area have zero movement?..."

My experience in that area has been with auto+O/D vs manual+O/D. But I would think the same rules apply. Yes it's absolutely possible to have a sloppy output bushing (bearing) with no oil leakage, as there is quite a bit of resiliency in the seal. You shouldn't be able to detect much, if any at all, play when you shake the yoke up/down/left/right. When mine went bad I experienced pretty much exactly what you describe, and yes, it increased with throttle load.

Thanks that's the info I needed.

I would think it may be a u-joint issue. Is it worst just before/after/at shifts?
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740T and 244DL - Frank the Tank @287K mi. and The Polished Turd @237K mi.

M46 so I shift but the worst is steady speed at around 60mph. Maintaining a steady speed it will vibrate then stop but this seems due to non flat roads so I have to apply gas or back off to maintain that speed. I'm going to pop the whole thing when I get a chance and hand check everything.
ian