1997 Audi A8Quattro in limp mode

[Wally Choate]

Background: I changed the AT fluid and filter but that did not solve the problem. In May 2009 it went into limp mode at 116,000 miles and I changed the AT fluid and filter to restore operation (the old filter was broken allowing crap to get through).
It now has 154,000 miles. It runs in reverse and high gear (limp). It starts off normally but soon bangs into limp. 
It's been garaged since I bought it in 2002 and mostly in a shaded parking ramps, has 2 new Michelin tires and alignment.

Thanks to Cody for the information on the transmission options and all the information from audi fans over the years, thus the reason to give it away rather than get $200 from a recycler.
I did find a rebuilt transmissions for $1800 but requires a method to get it off the truck and used one for $1000 in the exact model and year in Georgia but I have too many cars was thinking of selling it anyway.
How many miles can you drive these cars in limp mode??