The one point I would like to make in this discussion is that my 51 Chev 2 ton also has the air compressor. I have been under the truck many times and there appears to be no connection between the compressed air system and the truck's brakes. However, because the truck is setup to be a tractor, the air lines are located at the back of the cab. I can only assume this is for the air brakes for a trailer. Spanky informed me long ago that Bekins used many of these trucks and sure enough I can barely make out the Bekins logo on the front of the truck. So that's another possible use for the compressor system in these trucks.
Joe
