The "C" stands for conventional, or 2 wheel drive. The "K" is for 4x4 trucks.
10 - half ton
20 - 3/4 ton
30 - 1 ton
I'm not entirely sure on what the difference is between the 14/15 designation, although I know it has something to do with the bed style or length. I'm guessing that 14 is a short bed and the 15 is a long bed if my memory serves me correctly.
