Both are low drag options as much as I figured here's the excerpt from the text:
Originally, low-drag M117s were fitted with 52-lb M131 conical fins that were 49 in(124 cm) long with a 23-in (58-cm) fin span. In the early 1970s, the 64-lb MAU-103/B conical fin was introduced, featuring strakes, a 50-in (127-cm) length, and a 19-in(48-cm) fin span. A modified version of this fin, the MAU-103A/B increased fin-span to 22 in (56 cm).
The high-drag bomb, commonly known as the M117R, used the 117-lb MAU-91A/B
EDIT: Now that I think of it, why not attaching the whole document :D
Hope it can help...found in somewhere on the net, lost the link...
US Air Force Weapons.7z