This is one of the easier knobs to find in that it does not break easily and can be found on many 1967 FoMoCo products. Not used on Cougars with a center console and little to no differences can be seen between the different examples. One explanation for having multiple casting numbers for the same part is that Ford would use multiple suppliers for a single part. To differentiate which part came from which vendor, different casting numbers would be assigned. If there was a problem with a run they then could pinpoint which supplier was the culprit. Ford called this piece a "disc." If you find this absolutely fascinating like I do, then you really need to get out more!
Replaces part #s C7MA-18A932-A, C7GA-18A932-A, and C7AA-18A932-A.