Not sure if this is tandem forum group protocol, but on the Serotta forum (now called "The Paceline" forum, where I've been a member for awhile) is a gentleman who is selling a pristine 7803 group. Wish I had seen this a year or so ago, since I had wanted to use 7803 on my tandem but could not find enough parts in good enough shape to do it right.

Anyway, here's the link: