Within my data I find no conclusive mention of a further extension to July, 1941. There is no member road vote listed (via letter ballot) within the 1941 AAR Mechanical Division "Proceedings". Was this extension granted by the AARs' Board of Directors (as was the case in several of the previous extensions)? If July, 1941 was indeed the final date, can anyone here provide conclusive information via AAR interchange rules book and/or other data?
I have seen the 7/41 date documented but in searching in my (currently rather disorderly) files for the evidence, I haven't been able to find it. I'll continue to look for it, but I'm sure that mid-1941 is the correct date.