This vacuum can business gets more and more confusing the deeper we dig into it!
It might just be easier to start a thread with PHOTOGRAPHS of all the various vacuum canisters or combination of canisters that are KNOWN as original equipment for 67's and 68's...label them "Example #1", "Example #2", "Example #3" and so on.
From that point have every member with a 67-68 Mustang "TAG" the one that best represents their example followed with a "VIN, minus 3 consecutive digits" and at very least, a scheduled or actual build date, then include a check box style questionaire with "yes" or "no" answers including "Restored", "Unrestored", "Original Owner", "Factory installed Air Conditioning", "Tilt-Away Column", "Factory Installed Speed Control", "Dealer Installed Speed Control", "Other Than What Is Pictured Canister(s) present", etc. thus assembling a compilation of Data.
May be possible to do, and maybe we would then find out even more examples of alterations, thus helping to steer the "alterations" back on course, or more apropriately worded, back on Concours!
Richard
It might be possibly to nail down a few grey areas with such a document...but maybe I am dreaming