Hi Action,Interesting find.
There is a transistorized voltage regulator used from 1965 to 1967 with a 53 amp Leece-Neville alternator. Production installed.
And a second transistorized voltage regulator with a kit used from 1966 to 1968 with a 53, 60 or 65 amp Leece-Neville alternator or a 42 amp Autolite alternator. Consists of a regulator and a wiring harness. This would be dealer installed or sold over the parts counter.
All of the above data is from the MPC. No notation of Delco Remy as a vendor
Which one is connected to the alternator?
I saw the option in the '68 Service Manual, but unless the pictures were generic they do not match. Oh and both regulators were connected, that's what took me by surprise and made me laugh.