Hi David
Bob is correct your photos add to the knowledge base of the early side curtains. There are some photos of trucks with them in use but most don't.
The picture above is from a batch of snaps taken in British Columbia from the pictures is must have been cold because most of them show the side curtains installed on all the trucks.
http://canadianmilitarypattern.com/C...20Columbia.htm
Driving these trucks with the side curtains in is claustrophobic and greatly decrease the visibility.
Now the next question who is going to be first to reproduce the side curtains and take their Pat 11 or 12 out for a spin at -30C?
Cheers Phil