As a transmission man, my suggestion might not be the best for your situation. At this point, I'd start checking all the lines & seals (on some models, it's been known to loose the seal on the inner shaft keeper)...(That's the front inner-splinned piece on your drive shaft just ahead of the front universal joint, that slides over the output shaft of the tranny.......... Not all models will have it, but check to see if there's a little disk there to keep fluid from running out the back of the shaft. If there isn't a place where fluid can leak out of the shaft in the back of the shaft near the U-joint, then your's doesn't have this feature.)

After finding the leak, I'd drop the pan & check for excess (if there's enough METALLIC debris to cover a nickle, it's time for a rebuild. On the other hand, some debris is acceptible & clutch dust shouldn't be more than a teaspoon or rebuild).

This is a very straight forward tranny to rebuild (even if you never have, but get a book).
If you decide to rebuild, make CERTAIN that the selector valve link in the tranny (the book will guide you here) isn't misshapen or streatched. If you're even the least bit uncertain, replace it & by ALL means, replace the TC. The same rule of thumb goes for the check balls & divider plate. (again, the book will show you.

Here's the best place for a trans kit & parts if you do rebuild.
Trans Mart ph# 800-633-3340 (that's most likely not going to be the ncarest to you, but they'll give a number that is).
The next best is
Trans Star 800-321-8830 (they're a little higher on parts & their customer seveice is good, but Trans Mart's is GREAT).

Frank

BTW, the max amounts of debris I listed are for a tranny that's known run till the pump was dry, not all situations, just your's.
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85 740 gl NA manual trans 87 740 gle NA zf trans 88 740 gle turbo wagon AW trans, loaded & fun.