Recently, I got a braking system from a '66 pickup that consisted of the 6-7"power booster & Master Cylinder that is connected to a huge Bendix Hydrovac Booster that was apparently factory mounted on the driver's fenderwell. This is the same Hydrovac as listed in Volume 1 of the '66 shop manual. I was wondering first if the normal power booster & MC would work fine without the Bendix, and was trying to figure out why this truck had the Bendix. It was from Colorado, was this an option to give more power stops if the engine died? Does anyone have info on these units, maybe even what this option cost, and why in the shop manual it is referred to as "frame mounted"? This unit with it's bracket looks as if it was always on the fenderwell since day one. Any ideas??? My '66 has the 300-6 and I was hoping to swap in the regular power booster. I don't know if the 6 would provide enough vaccuum for the Bendix too..