Circuit diagram and components for Comfortron controller (Chevy, Oldsmobile, ...)
I agree that it is a good chance that it is germanium. There were not a lot of transistor choices in the 60's, so you may try any PNP or NPN germanium in a T03 and see what happens. Not knowing where the I/O ports go to it's a guess as to what it is doing.

I've been down this road before, only my "black box" was potted. If you can figure out the input sensors, and know where the outputs go to, then why not roll your own circuit? If you make it microprocessor controlled, changes are trivial to make. It is more involved, but if you do it right and with today's technology it should be even better than the original.