The Bill Blass edition Lincoln was never on a Town Car. It existed only on the Mark Series. It was started in 1976 on the Mark IV and ended on the 1992 Mark VII. There were 4 Special Editions introduced to the Mark Series in 1976: Pucci, Givenchy, Bill Blass & Cartier.
The Gucci Edition was only available in 1989. The longest lasting of the 1976+ Lincoln Special Editions is the Cartier Edition, which was moved from the Mark (1976) to the Town Car series in 1982 and was used until it was replaced in 2004.
If you want a unique edition TC, keep looking and you'll probably find a nice Cartier, Gucci, Jack Nicklaus or Presidential Edition ready to be bought.
Good Luck,
GT6