Found this thing in the junk today. It says "single channel linear power amplifier 800". Pretty beat up, like it may have had a ride out of a truck. The bottom is screwed on and looks to be about a 1 inch well for electronics with a 1 1/2 inch heat sink. Appears to be aluminum with gold plated plug on one end. I don't have time right now to take it apart, but will later unless someone knows what is inside. Total size is about 3.5 inches by 5 inches by 12 inches.
Big 'ole RF amp. Probably used by a trucker for a CB or ham radio setup. May have been mounted outside the cab because of the heat it generates. (Could have been tossed out if he was getting pulled over since the maximum legal wattage on a CB is something like 4 watts on AM or 12 watts on SSB, but that seems unlikely, as it wasn't a cheap piece of equipment).