Would anyone with expertise with the AW 71L tranny in the non-turbo cars please read this and offer opinions, please.

1990 745GL, no turbo. AW 71L tranny

When backing car out of the driveway one morning, wife noted that it got balky and jerky going up the uphill part of our driveway. Car was stone cold, had been sitting overnight.

I assumed the engine was signaling that it has been too long since I did the whole clean-the-throttle-body-and-check-everything-else service that usually gets the idle smooth again. Thinking this way, I told her to start the car the next morning, and let it idle for two full minutes by the clock to warm up a little and smooth out. It worked.

Day after that the car would not go up the driveway at all, even after idling for well over two minutes. Pulled it into the garage, and going forward in Drive worked just fine. With it pulled into the garage, it left a big puddle of tranny fluid. Although it looked like more that it really was, spills usually do. I found the underside of the car, from the rear tranny mount back, to be coated in enough tranny fluid to drip off and make the puddle. It looked to me like the tailshaft flange that attaches to the driveshaft (via U-joint) was bone dry. But the rear end of the U-joint was wet, and everything to the rear of it as well (driveshaft, chassis, etc.).

The tranny was about 2.75 quarts low on fluid. To check whether there had been internal damage, I topped it off and tried to back it out of the garage when it was cold. Worked like a charm, not even any nasty (= expensive) noises. I actually drove it about a half of a block down the street in reverse. There was no problem with Drive gear either, but that had always worked fine, even when reverse was balking or binding. There were NO LEAKS, but the tranny was nowhere fully warmed up either. The total run time was about 45 seconds.

Now I'm wondering whether just to find the leak and fix it (the tailshaft housing seal and gasket are prime suspects), or to haul it into a transmission shop. That is the question.

Also, while I suspect the seals/gaskets on the the tailshaft housing, it bewilders me that the flange at the rear of it (the companion flange?) seems to be dry, but the driveshaft immediately behind it is wet with tranny fluid.

Any insight or suggestions would be appreciated. On one hand I don't want to take it to a shop if all it needs is to have the tailshaft housing seal/gasket/bushing replaced (got my own hydraulic press for the bushing). On the other hand, I don't want to go to all the trouble of replacing the seals, etc. if it has to go to a shop anyway.

Thanks.
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1955 Human, Scott; 1991 745 Turbo, Brunhilde; 1990 745GL, Snuggle Bunny