I second eurekaprince's advice. I did something similar with Electrolux USA's lexan cleaners that hadn't been researched. I found how they were made in color sets and how model numbers related to certain features overall.
I also found old Vacuumland threads helpful; along with information from Doug Smith (big-time collector), John Anderson (long-time salesman), Jimmy Martin (long-time seller/service tech) and others who responded.
Additionally, literature such as user manuals and sales brochures provided data.
It took a long time, patience, and perseverance; but it was worth it.