I opened up a roll of T/T- B/U Wheats I purchased off of eBay for 15 bucks today and all were indeed B/U but 47 of them had too many nicks on them for me so they went into storage for now. Two of them were indeed flawless. the 50th one had this RPM. Thought I would share, for educational purposes. Looks like a Large D over a Small D.
looks like an rpm to me =) nice find. It is listed ad 1956 D/D RPM3 on http://www.lincolncentresource.com/RPMS/TOP50RPMs.html
