Winchester shotshell box question

Once again asking to be educated by fellow forum members. I am curious about white Winchester boxes with yellow x’s. Most white boxes have red X’s. What time frame was the yellow X’s produces? Any special meaning? Thanks again.

In 1977, when the steel shot loads first began to come out, Winchester-Western offered them in both WINCHESTER and WESTERN marked boxes which were the white-based box of the period. The WESTERN versions I have are Super X with the red X but the WINCHESTER versions are identical, except the X is yellow. To the best of my knowledge, Western boxes don’t have the yellow X. I have only seen a few of these boxes so I think it was short lived, at least for steel shot loads. I can’t say what the bracket dates may be.
This is a file photo of the WESTERN box that I think is one of the oldest steel shot offerings by W-W and the box I am referring to above.

The yellow and red color code was used to easily differenciate Westen from Winchester products. It seems that until 1970 the yellow color code was for Western and red for Winchester (i.e. Double A) but starting in 1971 the code changed to yellow for Winchester and red for Western (i.e. Double A, Upland).

After going through several catalogs and advertisements I’ve noted that the differenciated colors were first used in 1965 (i.e. Double A red = Winchester / Double A yellow = Western) and ended in 1978 (i.e. Super-X & T22 red = Western / Super-X & T22 yellow = Winchester). I can’t find anything before or after those dates.