You got it, Gary. Wires from unit were tape to upper radiator hose so heat sensor could monitor temperature and then modify vacuum to reduce emissions (supposedly). Car must have been in California as they required additional emissions hardware to be added to cars in the early 70's (had this exact unit on a Pontiac I owned and another type on an Opel). The Carter unit did not seem to adversely effect how the engine ran - the other unit on the Opel [drilled & tapped exhaust gas recirculator into exhaust manifold with hose to air cleaner] did NOT help the Opel run at all. Somewhere around 75-76 the state scrapped the law requiring and I took the junk off of both cars. Currently have a '58 Chevy Apache that has a NPT plug in its exhaust manifold so the owner of the truck at that time also had the exhaust gas recirculator installed.
Neat that you had the same set-up on one of your cars. Yes, it was in California. He said this car was purchased new in MN or WI (I can't remember which) but when it was a few years old the owner moved to California. He was guessing that the Carter setup was added at that point.
