Early GM replacement  AC Thermo expansion valve, which regulates the flow of refrigerant to the evaporator. 

 ON the body .. is may have stamped on it "34-50"

   (... if you have by chance.. stamped on it.. # "34-154" please contact us for an alternate.. and quote THIS # please.. PW11638)

 Although this is a GM part.. its been improved &  changed in physical design or looks slightly over the years but is the correct function part.

Fits but not limited to:

67-73 Camaro

66-74 Impala/  Belair Full size

66-69Nova

67-73 Firebird Trans Am

+ various GM commercial vehicles up thru to 77