Hi Larry and Bruce
Here is a shot of my 1941 Pat 12 C60L which was built with 16 wheels the photo shows it with 16 inch wheels on front and 20 inch rears. During the transition from the small wheels 10:50x16 originals to 11:00x20s.
Looking at the truck you posted you can see that it had the smaller brake drums need to fit the 16 inch wheel.
Telling the difference between C30 and C60 is difficult lacking the data plate. One of the best and easiest difference to spot is C30 did not have brake boosters and C60 did.
But once these trucks got into the hands of rebuild yards the mixing of parts took on a whole new meaning so most any combination was possible.
Good looking truck.
Cheers Phil