I'll send you some pictures this week of a dual circuit master that I have under my 46 2Ton with a vacuum booster. It's a 1.250 bore and is from a late 90's chevy 1Ton. I am using the vacuum booster from a 3/4 ton as the 1Ton's used a hydraboost and I didn't want to add a power steering pump! I am currently in the process of making a kit to convert the larger trucks to 15" front disc brakes, dual circuit vacuum boosted master that is kept under the floor and utilizes the stock rear drum's. You would need to run a residual valve on the front circuit to keep some pressure on the shoe's!
