Tranny Seals on 3sp auto-boxes

[Vikram Mittal <quattro@vulcan.gep.ge.com>]

I have a 1990 Audi 100 which also seems to have the leaking seals.
My mechanic (he was a Master mechanic at the local Audi dealer) 
tells me that this is a common problem with earlier years as well.

An odd symptom that the autobox displays is that the tran. fluid 
level goes *higher* than normal. I got it replaced and filled the
correct amount. The fact that it again goes higher probably might be
a result of the differential fluid (the synthetic one that was put in 
as a result of the recall) entering into the autobox side.

Has anybody got these seals replaced ? If so, did they do it themselves
or get a pro. to do the job ? How much did it cost ? 

Regards,
Vikram Mittal.