My 41 pickup fenders are different. The holes are round. I can't say what it is, but I can say it isn't 40/41 Ford pickup, or 46 up either because the holes are round in those too.
It does look like a pickup fender, though, due to the flat mounting face.
Sorry if this is not what you want to hear.
Mart.
Forgot to say, I did a video recently which shows a 41 fender in some detail. You will see what I mean if you watch it.
https://youtu.be/5Cn-PiffIlM
Edit2: Didn't see the link above!