i was wondering if anyone knew if on the vacuum pump in a 79 300d is supposed to have one or two hose ports where your brake booster and you air filter connect to it. if not can you use a y coupling

Two ports. One for vacuum and one to exhaust air to the air filter. Y is not possible since it would unite vacuum and pressure.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

damn well they sent me a part with one port on top is there a way to change some of the parts to

Did your old one have two ports? These early vacuum pumps are pretty easy to rebuild. It takes about an hour and you only have to remove the front cover, replace the diaphragm and both check valves.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

yes it did i just got them to send me the right one i would rather replace everything now since it is a new car to me that way i can be aware of when things were done i am also somewhat new to working on cars its my first one so it is all a learning process