'41 PU Rear Window

[Model51]

I don't have the specifics for the 1941 back glass bugs but I can tell you that for 1935-1936 trucks, the Ford oval was 1" wide and 0.56" tall. The oval on the doors and windshield glass is 0.69" c 0.44". Not sure why the rear glass received a larger logo but I've confirmed this with Ford Engineering drawings and several original trucks. Attached is a drawing showing the locations on the glass and the dimensions.
The sliding rear window used two identical glass pieces with the logo installed as shown in the illustration. This results in the logo reading properly on the right hand glass when viewed from the back of the truck and reads correctly from inside the truck on the left hand side (at least that's the way it was supposed to be done during production).
All this info is from the mid-1930's but probably didn't change before WW2..