Biglou55: First, thank you. I have it off the truck. The brass tag on one of the j-bolts reads #374000. Here is a picture of my hydrovac:
[img]
http://members.cox.net/brookebailey/hydrovac1951.jpg[/img]
I stopped in a NAPA store this afternoon in Grandy North Carolina and they didn't have anything on the hydrovac. Then I stopped in Pungo this evening and they don't have anything later than 1965. they said if I brought mine in, they would send it out to be rebuilt but didn't know how long that would take. I'd rather rebuild it myself if I can find a kit.
My truck is a 1951 2 ton 6400 series. Note: There was no C designation back then as far as I know. Thanks.