Stovebolt.com Forums The Parking Lot Big Bolts Can someone identify this for me?

I bought a 6400 with grain bed and hoist, 2-speed rear-end, and this assembly is on the firewall my question is what is this.

http://good-times.webshots.com/photo/2379570540102454676YQZtbb

Hy Brad Allen, that is a windshield washer pump, manufactured by "Trico" I believe, hope that helps.

I found this information in a GMC book can anyone help fill in the blanks on this, have you ever seen one? The last truck I purchased (1950 6400) had this vacuum pump booster on the firewall. It also had a small rheostat switch with VAC on the dial in the cab. I have found reference to this in my GMC parts book but not Chevrolet (GMC 23.3787 part #2233295) does anybody know how these worked or any more information on them. I assume it is a 6-volt powered vacuum pump that boosts engine vacuum like the optional fuel pump.

http://good-times.webshots.com/photo/2379570540102454676YQZtbb
http://good-times.webshots.com/photo/2145875240102454676VbBPfp

That is a "Trico" vacuum pump.
It assists the vacuum wiper motor with extra vacuum power.

They were also commonly added to truck tractors pulling trailers with vacuum brakes. However, they were just about as unreliable as the vacuum brakes were.