I don't know if it will fit or not, but when I was fooling around with
Mercrusiers, I bought an aftermarket shop manual, Clymer's, maybe? anyway
the manual gives a good history of the units and their changes. Just
recalling from memory, there may be a problem with some of the oldest units
accepting the Alpha. The type 1 isn't the oldest, I think, but I think the
Alpha will replace a type 1 The '66 may be prior to the type 1?
Good luck.

--
Ron White
Boat building web address is
www.concentric.net/~knotreel