I hope this will be of some help to those of you that are looking for a vacuum source for your A/C controls. At work we have 2 large Ford wreckers around (28,0000 GVW). They both have 6bta's in them. They have basically a P.U. cab on them with all the extras, A/C cruse control ect. I was working on the 96 year model last Friday and became curious about what they used for a vacuum source for all A/C ect. What I found was a very small electric vacuum pump mounted on the firewall just above the engine and also a small vacuum tank. It only runs when vacuum is needed and then shuts off. It appears to be completely self contained and the vacuum line ties directly into the small vacuum tank and then into the A/C system. I looked but did not find any part# on it but I suspect this may be a common part on larger trucks. Maybe someone in that field could help us out with a part#. If not I will research this a little more at my local Ford dealer if you guys would like me to.