It's threads like this that make me understand why DRMS is reviewing the "safety" of the EUC items!
The brakes on these trucks are late 40's technology, I would think any semi-experienced mechanic would look at any mid-60's or earlier car/truck brake system due to the single system brakes before they even attempted to drivethe vehicle. That is let alone on a 14,000 pound truck! I don't mean to be harsh, but there are alot of very experienced MV personnel on this forum where experience can be gained. Anyone can learn quickly just by doing some simple searches and researching topics and asking when you run into problems. The reason everyone seems rather boisterous about this topic is that an accident let alone a preventable accident can end our hobby. Updating the brakes (jake brake/stainless lines) are not always an option either. Several members have VERY rare or one of a kind trucks where that is not an option and an origional brake system is the way to go. If the brake systems are kept up they are safe. I NEVER drive either of my dueces without checking fluid and doing a thorough walkaround. As far as your truck: I'll bet if you fill the M/C up, (and attach a hose to the bleeders as you go to prevent fluid from going all over), and start bleeding with the airpack then go to wheel cyls like the manual says to get it bled correctly, then have someone stand on the brake pedal for a few minutes you will see the leak. It will either be in a line, wheel cylinder, M/C, or airpak. The system is very, very basic, but must be right before being driven. I have driven mine through Houston too, but you never know what is going to happen. I was pulling another duece 2 months ago and had a cop (imagine that) pull out in front of me. I was pulling myself up off the seat standing on the brake pedal. I barely missed hitting him broadside (think he had to clean his shorts). Moral of the story, you never know what is going to happen. Fix it right, and be safe!