Ding, ding, ding! Give the man a cigar - Kaiser-Fleetwings XBTK is correct.
The four aircraft were the Curtiss BTC, the Martin BTM and the Douglas BTD. The Curtiss was the last aircraft they would produce for the Navy, and the Martin became the AM-1 Mauler, a very large single-engine aircraft of which they produced around 150. The BTD garnered an order for 623, which was later cancelled. Douglas went back to the drawing board and created the BT2D, which became the Skyraider.
As for the BTK, it was a large aircraft and performed well, but only 5 were built. It had an unusual cooling/exhaust system which routed the outgoing cooling air and exhaust together in a duct down the sides of the aircraft, exiting behind the pilot. It was claimed that it reduced drag significantly and possibly added a little thrust. The 5 BTK's wound up serving as testbeds for this idea, although with jet engines eclipsing pistons, there was little future in it.
Interestingly, the Budd Conastoga was subject of a trivia quiz here recently. It was a stainless steel crago plane, made in Pennsylvania. Well, Fleetwings, beofre they became part of Kaiser, were mostly known for a stainless steel flying boat - The Seabird, as well as a prototype for a stainless steel trainer. They too were located in Pennsylvania. It seems that all the stainless steel aircraft constructed were from PA!