I see your point. This one is a sensor and the voltage corresponds to the reading and then a control unit takes decisions based on the reading.
For this application we need just a vac switch, no need to report a reading.
After reading this posts of yours, I started looking around here (Brazil) and found a bloke selling online new UP28 with the vac switch for "alternator vac pump replacement/conversion" on diesels. The price of the UP28 is actually very good. The price of the switch he sells is more then the UP28 itself. I am trying to find a vac switch that could be used for this at a lower price.
This is how he is selling his stuff. Pretty "rough"...
Here the UP28 is used on VWs like Jetta, Golf, Audi...
Attachment 85936
Still donīt know from which application he is taking this switch.
Attachment 85937