Obviously a 1958 Oldsmobile, but that's the easy part. There were several coachbuilders, predominently in the American south, that built professional car bodies on various chassis other than the typical Cadillac. One of these was the Comet Coach Company, located in Memphis, Tenesee from 1955-1959 before relocating to Blytheville, Arkansas for a couple more years. I believe this is one of their products. I've seen different photos of the same car where it is called an "Oldsmobile Royal Ambulance" . . . but "Royal" (or more properly "Royale Rescuer" was a trademark of Superior Coach, and this doesn't look at all like a Superior-produced car. I'll go with Comet.