Shawn, I had the dates flipped above. I went through the earlier PDF too and I grabbed full page ads with dates on them. The first two are from 1918 and 1919. To my novice eyes I do not see much that changes between the models, but it's only a few months difference; most likely, Hendee/Indian bought a year's worth of space in the bulletin and the changed a font size or wording to "freshen" up the ad.
The 1920 advertisement I found can be dated by the opposing page near the bottom where an entry begins with: "Fall Century 1920" that was from an October 1920 bulletin and the ad showcases the less deluxe model Indian bicycle. I also found a couple ads from 1914/1915 that are motorcycle based, but I'm adding them all here. I hope this helps!
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