Vacuum sensor, and maybe a valve

I am thinking about adding a vacuum sensor to the 4wd differential locking system on my truck, for troubleshooting purposes. Right now the system works by a mechanical switch in the transmission, that allows vacuum from the engine to pull back an actuator when the shift lever is in 4wd-LO. I would like to put this sensor: http://search.digikey.com/us/en/products/MPXV6115VC6U/MPXV6115VC6U-ND/951851 just before the actuator, so I can tell when the actuator is getting vacuum. The idea is that the Arduino would read this sensor (and a second sensor that checks for actuator movement), and light up an LED or something to show that the system is working. Looking at the datasheet, I can just use the analog pins on the Arduino to read the 0v - 4.6v provided by the sensor, correct?

Also, it would be nice if I could cut the mechanical switch from the transmission out of the picture, and use some sort of electric valve instead (there are many cases in which it is useful to be in a low gear without sacrificing turning ability). Anyone know of a good source for cheap electric valves that will work with a vacuum system?

That is a dry air sensor, so it should work fine for you. just connect pin 4 to a analog input on your arduino. remember that analogRead gives you 0-1023 output for 0-5v input, so you may need to map to a range indicating actual vacuum, unless you are just looking for a go/no. If that's the case, you might want a vacuum switch instead of a analog unit, or look for a range (0-500, no/bad vacuum, 501-1023, good vacuum).