Speaking of the 580 class, of which there were three (Barbel SS-580, Blueback SS-581, and Bonefish SS-582), my boat the Blueback is considered the LAST diesel sub in the US Navy. By her number, you would think it would be the Bonefish, because the Blueback's keel was laid (that is when they are assigned an SS number) before that of the Bonefish, but, the Blueback was the last to be commissioned. Blueback was built in my home town of Pascagoula, Ms, at Ingalls Shipbuilding. When I was given my choice of subs after Sub School, I jumped at the chance to serve on the Blueback. My father was a high exec at Ingalls. The Bonefish was built at New York Shipbuilding. The Barbel was built at Portsmouth Naval Shipyard. I guess the Navy liked to spread around the wealth back in those days.