They can be rigged to run for a short period of time with thrust bearing failure.
Hope its not your car's issue. (There is only one other item more crucial than endplay that you need to address --- fuel hoses --- they MUST be replaced if original post-haste --- incredible danger.)
The flexplate load-up / thrust bearing wear issue is serious, recognized and real --- to the enthusiast who studies the 928. Many shops have no clue. Its automatic cars, not 5 speeds, unlike detroit stuff. Cars have shown failure with 40K miles. As time has progressed, it seems more cars are failing.
You need to disassemble the front suspension, remove steering rack, alternator and crossmember to access the pan efficiently. Skip it.
Drop the exhaust a bit, drop the bellhousing cover, remove the pinch bolt and use a tire iron and dial gauge to measure crankshaft endplay (fore/aft). It will be virtually definitive.
You can also cut-up and inspect the inside of that oil filter.
Here is the thread you need next.
My Flexplate - Crank Endplay Check Pictorial - Rennlist Discussion Forums
This is helpful (auxilliary clamp), in the event your endplay is ok ---
My PKlamp Experience - Rennlist Discussion Forums