The parts are the tailshaft bushing and seal. The seal is what's leaking- the bushing has worn enough to allow excess shaft play, wearing out the bushing.
A shop that services Volvos should have a bushing puller tool. It turns this into a 45-minute job (tops). The seal and bushing together list for $37.50. From FCP Groton or similar suppliers, probably half that. The tool is about $80. Without the tool a shop has to remove the rear transmission housing and replace the big paper seal on it's face (A PITA if there ever was one), AND you have to press out the bushing. IPD has a picture of the tool on their website (I think it's in a PDF file). Print it out and see if the shop has ever heard of such a thing for these transmissions. IT services the Aisin-Warner AW70, 71, and 72. If they look at you funny, they don't need your business. Our shop used to charge an hour's labor for that because we had the tool. Without it, it's 4 hours. That's almost $200 more on your bill - so shop around! Any Volvo shop ought to know about this. The tailshaft seal is a REALLY common place to leak. Just replaced the one on my 1987.
Good luck!
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE, 91 244: 808K total