I sent this to Bob Grellman this morning so he could take a look. Both he and Tom Deck (both highly respected by the Collector community at large and by me) have the initial impression it's a S-174 from the photos, but I don't think this will stand up to closer scrutiny. We'll see what he says.
Well, it's not the 1798 NC-3 I was hoping for. It turned out to be the S-167 E-MDS which was suggested by Mark and Cerdsalicious. The Leaf at T merging into the stem and the lack of the prominent die crack at the triple leaf had me fooled, but it must have been just wear.