Be careful, the new seal has a lip, and requires the new type flange with a groove to accept the lipped seal. This was re-designed in recogniton that the old design was too prone to leaking.
I dont know if you can still get the old type seals. From my experience I went to a place that didnt know, and they stuffed the new-type seal into the old flange, which obviously deformed the seal. Needles to say it was leaking again within a year or so. Next time round I went to 4Rings in Dartford and they put in the new type output flange as well, which costs around £120.
This:
http://forums.quattroworld.com/a8/msgs/32544.phtml
and this
http://forums.quattroworld.com/a8/msgs/56848.phtml