71 c-10 w/cab marker lights

[70k52wd]

I'm going to go look at this 71 I found on CL. It says right on the spid, "marker lamps". I know you could special order all kinds of combinations back in the day. This I would think is a strange option for a c-10. Would this be a c-20 or c-30 cab that was moved to the c-10 line? Are the cab mounts the same for the c-10, 20, 30? For some reason I was thinking they were different mounts. What do you all think? any opinions on this trucks options? It also has a spotlight, and had dealer a/c. The a/c is gone, but owner has the paperwork stating a/c was on it. Just thought it might be a pretty cool truck to use for a daily.
http://washingtondc.craigslist.org/m...425429578.html