They were avaialble, the 1954 Assembly Manual shows really good views of it. I have owned 3 all on big trucks 1-1/2 ton or above. Factory part number is 3705063.

http://good-times.webshots.com/photo/2673348600102454676qtmVHy
http://good-times.webshots.com/photo/2978230330102454676lGnkQb
http://good-times.webshots.com/photo/2705488650102454676sLCmCA