I have it tore down for all new lines, hoses, cylinders, mastery cyl etc. My truck has the usual Hydrovac mounted under the cab it's a double diaphragm unit. The back axle brakes are operated from a second hydrovac unit with a small master cylinder on it with it's on reservoir. I am going to get the main Hydrovac rebuilt or get a rebuilt one. I don't see any listed like the back one when I look online. Did all tandem axle trucks have theses? I don't see it listed in the service manual. It doesn't look it it has seen attention for many years.
It's a tag. I will look again at the spec tag but I believe it lists the tag axle on there. The axle MFG tag says it's made in Alabama. I need to clean it off better to get the name. Tomorrow I will get pics of the Hydrovac unit with the small master cyl on it and the axle itself.
