Fan Clutch "CV" Ink stamp ?????

[CamarosRus]

Russ Guajardo has told me .............

"The differences in the fan clutches can be either external in fin configuration, models of cars assigned to, or different production runs by eaton. I was speaking only to the internals on these in my first response, the internals are exactly identical"

Can anybody explain why and or confirm if ALL the 7" Fan Clutches in 1970 were stamped
CV as Ive seen on the Z28........and CZ on Big Block......WHY if its the same internals and same external ............

And how is the date coding broken down on the EATON Fan Clutch