Les:
You can use a C9 motor in a 1959 machine, however, you would sacrifice the blower feature. A 1959 motor can easily be installed in a C9 if you remove the blower shroud (2 screws).
You should see all the binders FULL of vacuum materials, owners manuals, etc. I've been collecting for almost 50 years.
Someone asked me if I thought about putting out a newsletter. I have so much stuff I could do that for years. One day you'll have to visit. There's a Staples across the street for color printing and I have a printer here at the shop. You're welcome to make copies of anything you like. The folks who come to the Vacuum Cleaner Collectors Conventions usually spend hours looking through all the printed materials I have.