Back in the olden days Schlage published service manuals for each product series. This listing is for the C and D series Heavy Duty Cylindrical locks. C Series locks were the same as D series locks, except made of non-ferrous materials - the locks would not rust.

Also of note is that this book references Schlage original product numbers, not the ones they have now with the dash as part of the number. A cylinder for a D knob lock is not a 23-001, it's C2381. Remember those?

This is a piece of history that should not be lost.