Exhaust brake is basically a valve (butterfly or guillotine) that blocks off the exhaust flow creating backpressure in the engine and slowing your vehicle down. There are several types from manual or cable actuated, electric valve or air operated valve (i'd recommend the air since you already have an on board air system). Some trucks have vehicle specific brakes like the Ford Powerstroke and Dodge Cummins that mount directly to the turbo...we ain't gonna find that for the deuce. That's where the remote mounted units come in, they simply remove a piece of pipe 8-10" long and installs in place of the removed pipe. Plenty of room in our engine compt. to mount one.
Now there is some wiring involved, an on off switch to turn the unit off when you don't need it (They spend most of their lives in the 'on' position). Now there are two ways that you could wire it up, either use a throttle actuated switch that would activate the unit as soon as your foot is off the throttle, or a push pull type switch mounted on the gear shifter works nice also.
Hope that helps a bit, my eyes are so tired I can barely keep them open right now.