hello i am working on the brakes on a 1941 Mack Ce firetruck. I am looking for information on the vacuum booster for the brake system. The master cylinder is mount on the frame just in front of the left rear leaf spring and has one brake line that runs over to the booster that in mounded just in front of the right rear leaf spring. The booster has one brake line that runs to a Y that then runs to the front and rear wheel cylinders. The booster looks to have 3 vacuum lines running to it. The wheel cylinders and master cylinder are leaking and im going to sent them out to be rebuilt. I was wondering if i need to have the booster sent out or if i can just flush new fluid throw it .