If you go to the bottom of the linked page from my original post, it gives directions to build the necessary shunt.
It appears to be a proven design.

I guess that since no one appears to know the part number of the unit Chevy used, I will have to order the components on line and build a unit for myself.

I will post the result.

1957 Chevy 3600

At these prices I want my gas 100 octane, leaded, and my windshield washed!