Looking at this item again, I see from the 60-68 MPC that there are three, not two, different hinge assembly part numbers per side.
1. Before 7/17/67 = C7ZZ-6522810-A/C7ZZ-6522811-A
2. From 7/17/67 = C7ZZ-6522810-B/C7ZZ-6522811-B
3. 1968 = C7ZZ-6522810-C/C7ZZ-6522811-C
I was thinking that the common understanding was two versions, early cast versions changing over to stamped versions. Does anyone have any idea on or examples of the third variation?