A new OEM General Motors Thermostatic Vacuum Control Switch that I got at an auction of vintage car parts.  This is GM part no. 355963.

For use on some 1975-87 Chevrolet and GMC Trucks, but you will have to verify that this is for your application.

car auto automobile automotive classic emission pickup pick-up 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 75 76 77 78 79 80 81 82 83 84 85 86 87