What book? Looking in both The Sight Book (Madis) p 153 and Old Gunsights and Rifle Scopes (Stroebel) p. 26 list only the 1903.
In the Lyman chapter, Stroebel omitted the Model 63. If you look in the Marbles chapter, he correctly listed the W8 sight for both the Model 1903 and 63.
WACA 6571L, Historian & Board of Director Member