I recently purchased a complete Jam Handy filmstrip set designed for Chevrolet dealership mechanics.
https://www.flickr.com/photos/advance-design_parts_co/albums
I have compiled five so far from the set of 35, there is some good truck content for the 1939-early 47 crowd. Topics include The Wiring System, The Generator Regulator, Shock Absorbers, The Steering Gear and The Four Speed Transmission. These early strips are well past their design life and their condition could best be described as fragile.
https://www.flickr.com/photos/advance-design_parts_co/46340962941/in/album-72157631872034068/