Ditto. The vac switch by itself will not make the overdrive work. Are you saying you bought the car with this combo and it worked but you need to reconnect a hose to the vac switch? Look on the passenger side of the transmission for extra plumbing and two oil pressure switches and wiring or extra switches in the car to manually control it.
I bought the car with the combo and this whole time the switch was sitting there without a vac line connected. The overdrive has always worked though, and I will try to get a pic of it there are pressure switches on the side of the transmission