Hi Bob, no...this is a new motor and not one of the GM ones. This is the type sold on eBay, Amazon and elsewhere and looks like this: https://tinyurl.com/t4z65t3

4 wire switch: power, low speed, high speed, park. Park is disabled when the wipers are working and enabled when the wipers are switched off. That's the part I missed earlier...and 20 or 30 years ago something like that wouldn't have gotten past me.

Before going to sleep last night, I had the idea that the answer might lie in 2 relays. I know...that sounds strange, but I think it might be the answer. One to energize the motor winding (a normally open relay which is closed by the intermittent circuit) and the other to disable the park circuit (a normally closed relay which opens for the intermittent controller's pulse and then closes). I'm going to try that idea later today or tonight.

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end