20" S2 Rim - Outside Stamping

[427Krate]

Hope this topic hasn't been covered, I tried searching to no avail.

I have an 20" S2 Rim and the Schwinn S2 stamping is on the outside of the hoop, instead of in the center. All the other wheels I have show the stamping in the center. Is the "outside stamp" wheel a reproduction or off a later year stingray?

 

[GTs58]

I believe it was late 1965 or 1966 when Schwinn started side stamping the rims.

 

[72runner]

I believe it was late 1965 or 1966 when Schwinn started side stamping the rims.

69 side stamping started for s-2s 66 for s-7s

 

[Avanti]

69 side stamping started for s-2s 66 for s-7s

Do we know exactly when in 1966 Schwinn switched to side-stamping S7's? Was it at the beginning of the model year (January) or some time into the production run?