Basically, there are 2 types of "DC" wheels. The first ones, 1967, have a larger font. The 68 and early 69's were also coded "DC" and the font was smaller. There is no such thing as a 6 1/2" or 7 1/2" inch DC wheel. They were all 6", period. There was a "DB" coded wheel in 67 that was 5" wide for use on standard disc brake cars. These wheels were all welded. The 15 x 6 riveted wheels were often found on Corvettes and were coded "FI".