1941 trucks, at least, had no dipstick tubes. That would explain the shorter dipstick and smaller hole.
Holy Coy Batman!!! Now that is one of the funniest things I have done in a long time!
I put the shorter dipstick in the block and guess what? It shows that the oil is full (yes - I have 5 quarts in it!).
Thanks - Sometimes it's those really hard things that stump ya!