Help identifying unknown prop w/ hub markings

[Epphilippsen]

Hi, I’m a know-nothing about propellers. Zip. I did try and find identifying information online but quickly realized it would just be better to ask those who know. So, may I appeal to you knowledgeable ones in helping me identify a propeller that’s for sale in a little local shop, please?

The wooden propeller is:
- 6 ft long
- made of a light wood.
- It’s hub has 6 holes (I believe it is a “modern” type).
- there are no manufacturer decals on it although, based on a lighter-colored spot, it appears to have had one.
- the hub has the markings “68 SML 34 540” clearly imprinted on it
- the 2 leading edges and ends are covered in metal although one edge is damaged from something hitting it.
- the tag on it says it’s a “WWII spotter plane prop” but I thought I’d check or look into it.
- So, it’s not perfect but it’s neat in its own way.

Can you help me identify it, please? Thanks so much!

[Dbahnson]

When I go through all of the drawing numbers on this list I can't find any of them that begin with "68" (presumably the length in inches, not six feet) and I don't recognize the other number sequence, so my guess is that it is either an ultralight propeller or a prop designed for an airboat or other non-aircraft usage. A picture might help since airboat props have a fairly characteristic design.