NOTE: The three port vacuum switch was obtained from a wreckers yard, and this is probably the best source of supply. It can be found on pre-computer cars that are fitted with an EGR. Several manufactures seemed to use them. After several hours of internet search, I came up with only one listed part number. #TDA 932 manufactured by TECALEMIT. I have not seen this part, but based on their spec. it should perform the correct function.