Lang, I dont know much aabout vac brakes, but I wonder if you can find old compresser hose like they used on mobile compressors for jack hammers etc, I have some that wont go flat even if you drive on it, awful dirty black rubber stuff to use (makes everything black) but would definitely not suck flat. The acco and the C line had the same stuff in red for a vac trailer set up.
Lang, it's always puzzled me why the front of Army trailers are curved.
Is it because of kit stored behind the cabin?
Obviously you can pack less gear inside the front of the trailer being curved?
I'm sure you have the answer!
The reason was to get a turntable close to the cab on very short tractors. If it was square the corners of the trailer would hit the cab during a turn.
The whole thing was a waste of time because nothing that short eventuated (even the very short C60/F60 Blitz tractors) and a normal square trailer could be used. Apart from the inconvenient shape for loading you lost quite a few square feet of floor space. They put a spare tyre on the front of the round trailers No.3 which gave up all desire to come up close to the cab. Many transport operators and cockies built add-on corners after the war to make the round front models look "normal".
Trailers No. 2 had round end
Trailers N0. 2a had square end
Trailers N0.3 had round end
Trailers No.4 had square end
Trailers No.4a had square end
Apart from minor details all trailers were almost identical in all design features and parts were interchangeable. All built in Australia by McGrath. Freuhauf in USA built very similar shape and general design trailers for the American forces.
Hey Lang, before you buy any, let me see what is kicking around the shed.
Pretty sure you'll find one of those vac trailer brake thingo's at Prices.
You could always convert it too air, I've probably got all the valves for that, and air tank and boosters.