From what I just read about it I can't tell on these pics. Here's what I was looking at: https://www.pcgs.com/coinfacts/coin/1939-5c-reverse-1938/4003. Best you diagnose it yourself, you got it in hand. Nice find, Sherlock.
I did look on PCGS and can't really tell the difference %100 thats why im asking for more opinions best pictures I can do.
Some of these transitionals are like that. But you're just looking for the ones before the steps were tuck-pointed. I think the experts theorize they did that because too many people were falling going down the old steps.
Your specimen is the more common 1939 with the 40 Reverse. You can tell by the S in PLURIBUS. It is the notched S and not the smooth S found on the 38 Reverse.
The member to thank is @coloradobryan. He published the S diagnostic since for most circulated specimens, the steps are too worn to tell that way. There is also a notch in the T of UNITED, but that is often times too worn to. So the S is the best/fastest way to make the call.