You didn't say what year your Tugger is. You can still get rebuilt Hydrovac's to fit 1950's trucks from NAPA.
Before you replace the MC you will need to know the size of the wheel cylinders and how many there are.
The Hydrovac is nothing more than a Booster, when you press on the brake pedal the Hydrovac piston pushes it's MC for added system pressure. I think I read somewhere the Hydrovac adds an additional 900-1000 pounds of pressure to the system. If your truck has a firewall MC with a booster then you get the added boost from it first and then the added boost from the Hydrovac.
I agree with Jerry and Randy...will be way cheaper to repair the existing system than to try and engineer something else.
Mike B
