I have a '49 Chev panel that I've only owned for 3 months. I just woke up to the fact that only the driver's side door has a vent window and the passenger side window does not. DUH!

Did some panel trucks have right side vent windows and some not? Was it dictated by year of manufacture?
Lot's of vent window posts on "search" but could find nothing on my specific question.
Any help appreciated....
Jerry
Gilbert,AZ.