Transmission Controlled Spark Thermal Plug

[92470]

I know everyone will scream WHY! when I ask this, but does anyone know what the part number was/is , or where I can buy the thermal switch that screws into the passenger side head that was part of the TCS system? I have a 71' Super Cheyenne 350 4bbl/TH350 that is 100% stock with 99% of everything working on it, other than me not being able to find this thermal switch to complete the TCS system and the truck. The TCS switch on the tranny was easy to find, but this switch I can't find anywhere.

I know it cuts fuel mileage, probably would hurt more than help,is regarded by most as useless, and probably wouldn't even work as intended but I'm a purist I guess and not being able to find this is driving me crazy. I found one on a Corvette parts site for the 71' Vette, but it operates a little different. I've looked everywhere and can't find one or the part number. If anyone knows how to help, I would really appreciate it. Thanks!