64 Speedo question for the techies

[Deanoko]

As I am embarking on adding Cruise to a non cruise car, I'd like to know if the associated speedometers are basically the same with the cruise module bolted to the back, or are they more bespoke?  Photos would be helpful.  Thanks!

My 64 came with 19 options.  I'm working on getting it to 22...

[XframeFX]

For the early Rivieras, a non Electro-Cruise Speedo has the "Speed Minder". It appears to have a similar setpoint setup as the Electro-Cruise. However, the latter has an oscillating cam for it's crude transducer with the hair-spring wound in reverse to the Speed Minder.

 

The original in-house Buick Electro-Cruise locks on road speed by Speedo Needle position. Except for maybe the underhood actuator, totally obsolete by 1968 and not compatible with any other system except for a snow brush jammed between the driver's seat and the accelerator pedal! Even an original cruise switch is only compatible with Electro-Cruise.

The other GM divisions during that era chose to use a Perfect Circle product which counted pulses from speedo cable rotation. This system evolved with "Accelerate and Resume" in modern cruise controls meaning before ECM modules that we have today. 

 

For a universal cruise control, there's this:

https://www.rostra.com/universal-aftermarket-cruise-control-by-rostra.php

 

[Deanoko]

I was able to source a '64 cruise speedo out of Canada for $40, so will be able to place them side by side and make a detailed comparison.  I'd like to think that GM was thinking economy of parts here, and that translates into the vast majority of the  speedo mechanism being interchangeable.  "News at 11"