Does this mean that only the bottom half of these distributors
is valuable? What about the shaft? I ask because these distributors
are (at least in the 4cyl cars) almost identical to the distributors
in VW air cooled cars which are pretty common. The top half of them
looks pretty similar to stuff in mercedes benz cars of a similar
vintage (all of which have blue coils as well, I might add).

So, is it possible to make a "1975" B20 distributor with a shaft
from one source, body another and so on?

This is probably how bosch made them in the first place, so it
isn't totally wacko to think this...

Oh, and later on VW continued to make air cooled motors in mexico
with electronic ignition, complex modern fuel injection and so on;
I bet one of those ignition systems would work as well. An added
bonus would be knock detection.
chris