67-77 , , Engine Vacuum Check Valve. 1 Piece. This is used on all A/C 64-79 cars and 68-69 hide-a-way cars and also all firebirds off the vacuum tree the front of the engine. This has been discontuned from GM and this is a new reproduction. This is inline tube reproduction of the original. is the exact size and shape made with the 2 color plastics. These are the details that separate the first place cars from the rest.