71 valiant paint code question

Alaskan TA is correct. Here is a link that shows the GW3 color code, 1971 Plymouth, "Sno White". The same color was called "Bright White" by Dodge, and was not available on a Chrysler.

https://www.hamtramck-historical.com/images/dealerships/FleetBook/1971/71_Fleet_Colors_tops0001.jpg