You are looking at a super rare "official" Western Gear hydroplane gearbox service manual for the very gearbox we use on the Squire Shop V-12 Rolls Royce "Merlin" engine. As soon as I saw it, I snatched it up. Early indicators imply this likely originated from the Slo-Mo-Shun V team sometime back in the 50's.
An amazing find and acquisition no doubt, and it's something we can still use to this day.
PS: I'll have the next restoration posted by the end of the weekend, stay tuned...