I just bought a (used) Gretsch G5123B which the previous owner strung with flats -- which is what I would have put on there myself anyway, so yay -- but the previous owner doesn't know what kind of strings they are. They're, I would guess, .055-.110 flats with green silk at both ends. Pretty high tension, especially given the fact that they're on a medium-scale (32") instrument. To my ears, they seem to fall less on the thumpy side of things, with much more growl than I normally associate with flats. Any ideas?