http://www.fifthaveinternetgarage.com/
Available here any time for $US10.00 plus the usual shipping etc., no need to wait for an auction. I haven't dealt with them but they've been advertising in Hemmings for quite a few years.
They also sell alternator pulleys to fit a variety of belt sizes and brackets to mount alternators to either Chev of Ford engines of the vintage used on CMPs.