gmc has an intake manifold that has one to three ports on it(depending on vintage) that screws into the intake manifold on the engine. one port is for the hydravac, one for the two speed rear and one for the wiper. that fitting came off a 46 350 and is on my 40. the ashton is a little different. it has a fitting that screws into the manifold then a hose goes from there to the firewall where there is a manifold there for everything you desire. all you really need is a fitting and vacuum hose to get from the engine to the firewall to make your connections.
