ARG-6 and ARG-7 were sent drawings for 31/6Ax on 4/8/44, but the memo of instructions listed them as 31/2Ax, probably a typo, since the 31/6Ax drawings were used.
A starboard photo of USS Culebra Island (ARG-7) at Norfolk on June 11, 1944, wearing camouflage 31/6Ax. The vertical colors are ocean green (5-OG), navy green (5-NG) and dull black (BK). Photo taken by USS Alcor AD-34. Photo source: NARA 19-LCM-ARG7-2.