My father has been looking for the sixteen sided Rubik's Revenge
for years now. If you have any idea where I can get one for him
please let me know. Thanks for any help you can give.

Me too. Somebody posted this information some time ago in the cube-lovers
list...

<http://www.puzzletts.com>

It's a shop with Rubik-related puzzles, among others, including

#130 Rubik's Revenge (4x4x4)
#131 Professor's Cuve (5x5x5)

They sell on the Internet, too. They also have a complete list of
distribuitors worldwide, including

*Game Preserve
222 D Street, Suite 4
Davis, CA 95616
USA
Tel.: (916) 753 42 63

*Star Magic
4026 24th Street
San Francisco, CA 94114
USA

Greetings,

Alvaro