The 69 reverb unit is housed in the same case that was used for the multiplex amplifier on Stereo radios in 69.  The photo is of the multiplex but I also have a reverb but I don't have a photo handy.  The reverb unit doesn't have any external heat sinks and has a wiring cable attached.  On A, F and B bodies it mounts over the glovebox and on the GP it hangs under the radio in front of the console.