The empty holes in your frame that you have numbered as #2 are filled with rivets that hold the battery box on my frame. (The rivets look to be original.)
I now see your "Oops".
Attached is a photo of my frame with the holes/rivets numbered to agree with yours.
Nick 1940 KC Model 1/2 Ton Pickup Project (with '37-'39 Bed and what we think is a '42-'46 Frame) Taos, New Mexico
