So...question...after seeing this post and having no clue about the series 101-180 I went and looked at my set to see if I had any. In the first few pages I have several "white" backs, which are clearly white and pronounced. In the 101-180, I have three that stand out. They are quite duller than the first series white backs, but look more dirty white and more subdued. They certainly stand out next to the gray backs. Are these indeed white backs from the 101-180 series?
Card #134 in this pic -
Card #139 in this pic -
Card #172 in this one -
Again...the 3 cards seem to be in the middle...and definitely stand out. Sorry for the poor pics...