Located inside the air cleaner with two hoses attached underneath.

Also what is the purpose and where can they be bought today?

 

It is a thermal vacuum switch. It operates the door in the air cleaner snorkle. It keeps the snorkle door closed to pull hot air off the exhaust manifold until the engine warms up. Once the engine is at operating temp, the switch allows the snorkle to pull fresh air. If yours is broken, here is a link to a new one:
https://www.ebay.com/itm/324113454980

 

^^^ Air cleaner thermal vacuum switch.

 

Matter anit-matter space kabobulator....
Seriously thou...I see a couple on evil bay if you need one.

 

Kunuter valve.

 

Thanks everybody I snagged one off eBay...!

 

Old-school analog version of the IAT sensor.