Many aviators in Navy dirigibles wore them. There was definitely more room in an airship gondola to wear a long M-69 then inside a cramped bomber cockpit. I've also seen photos of Navy officers (Captains and Admirals) wearing them in extreme cold weather climates (such as the Aleutians).
And the Navy's sheepskin jackets were the M-444 and M-445.
Thor, I'm not sure, but isn't the M-445 the same as the AN-J-4? If they are, I could get a repro of one of those.