pollution controls, how to run the hoses

[mike16]

I got a 72 307 half ton with 3 speed. Alot of whats under the hood is origional. I want to keep it that way. What about polution controls. Mine is not an CA truck. I got a switch on the tranny sid cover that I thought was for back up lites...wrong Huh? and the electrically operated air valve thingie that goes between the vac advance and the carb and som evap canister. Its all there but whats it do, how do you test it for correct opps and how do you route the hoses correctly and if need be where are new NOS parts available.

Expound please.