Capt. Chris - I was mistaken. The sheath is stamped 5 5 on the back (and it is roughback). I have attached more photos of the blade and the back of the sheath. Do you think the sheath and knife are correctly matched? It wouldn't be the first time I bought a knife with a non-original sheath.
I guess I'll have to change my designation of this one to a #5-5!
Thanks for your comments and the photos.

- Bruce Buckner