Did a little more digging based on the USN markings on the mags. Lawrance built a Model 30-D APU. There are some pics of it out on the web but they all have their cooling shrouds installed and are complete so the engine details are obscured. One source stated they were used in Mariners and Privateers. Again, the Pensacola Naval Air Museum might be the best source of info. Even found one for sale about 15 miles from my location. Current bid was $750 and that was for a complete but unrestored non-running unit.
So with that said, the GJR’s pics maybe the engine portion of one of these units. Haven’t a clue of its worth as a collectible.