You have the vacuum pod brain under the hood with the speedo in and out hooks to the throttle with a cable.

Then you have the switches on the turn signal and power up with a brake light switch interrupt .

All plugs into the unit under the hood, if the power is getting to the unit should work, wiring can be found in any vintage 70's wiring diagram.

Not hard to add if you have the parts, going to try it on my 57 Willy's with the 4bt diesel, just need a working vacuum pump