Had the same problem when I changed my 1967 to 1972 disks. I used rotor/hubs drilled for six lugs so that I could keep the original 1967 5 1/2" x 15" wheels. Wrong! I solved the problem be using 1971 through 19?? four wheel drive 6" x 15" rims. Look stock and have three "nubs" for center caps.