Johnny Cash, Linda Ronstadt and Roy Clark – NAPA Presents A Concert: Behind Prison Walls (1978):  Every once in a while, I come across an album with a corporate label; and just for fun, I have picked up several of them.  Despite the title, this is a selection of studio recordings of four familiar hit songs apiece from three music giants who have regularly wandered across musical boundaries over the years.  Not even Johnny Cash’s “Folsom Prison Blues” is a live recording, though that is hardly a detraction – as best I can tell, this is the original 1956 rockabilly recording of “Folsom Prison Blues” that dates from Johnny Cash’s days at Sun Records.  There was an actual “concert behind prison walls”, however – due to Johnny Cash’s electrifying live performances at Folsom Prison and San Quentin Prison in the late 1960’s, a concert at Tennessee State Penitentiary by Johnny Cash was televised in 1976, with featured guests that included Linda Ronstadt and Roy Clark.  The soundtrack, A Concert Behind Prison Walls was also released in 1976.  I haven’t studied the matter, but not even the songlist on the two albums appears to be the same.