Thanks guys! The shop manuals have been ordered, just haven't come in yet. The truck is a 48 1.5 ton Chevy. It sounds like I've got the Hydro-Vac system. I've got a new master cylinder for the truck that I plan on installing this weekend. Also going to replace the wheel cylinders too, because this truck was parked years ago due to brake problems. I did a quick visual inspection of the lines, and they *appear* to be solid, but I do need to give it a more thorough look when I tear things apart this weekend. Hopefully I'll get lucky with the master cylinder/wheel cylinder replacement and bleeding the lines and this will fix the problem. But if not, no big deal.. just keep replacing the bad parts until it's fixed. I got it running, now just have to stop it.
