If the truck doesn't have one, it would be a good idea to add a vacuum reservoir tank. With a one way check valve between the engine and the reserve tank you'll have a couple of brake applications available, and/or smoother rear axle shifts. I like to use a recycled Freon gas tank. Most refrigeration shops will give you one (or several) since empties are usually discarded, not refilled. With some flat steel strap mountings, one or two of them fit very nicely inside a big truck frame rail.
Jerry
Can you post some photos of this setup?
