Hi David,
I do have a source for an electronic cruise control that does not use vacuum to operate. Here is the link:
Rostra Cruise Control Just to make sure, I have no interest in this cruise control and will make no money on it if anyone does go and buy it -- just wanted to be clear on that.
You can use the cruise switch that is mounted on the dash, or go the expensive way that I went and change the column and everything to something that is more 1970's looking. Yes, I went with a 1971 New Yorker tilt column and got to pay to have the horn relocated to the center of the steering wheel (but it is integral to the Mopar turn signal switch, so that helps). The cruise control switch from 1971 looks right in the car, and still operates the Rostra electronic cruise control -- at least in theory. Have not tried it yet, but it is all set to try when the time is right. There are two other switches that are installed, one at the brake, and the other on the tach to turn off the cruise with a spike in the rpms, or if the brake is depressed. David, you will have no trouble at all figuring this out. It is very easy to understand once you get the schematic in front of you. All simple circuits that home run into the servo.
Sorry about another hijacking in so many days; but I wanted to answer the question that I have been studying for it seems forever.....
Have fun,
Mark