Thank you! A very interesting page.
And an example of what I mean - sources are wildly contradictory. From your reference:
"The A.A.R. began a program of consolidated Stencils in 1972 which applied
to new or rebuilt freight cars only. Application to existing cars was not
mandatory. The F.R.A.(Federal Railroad Administration)created in 1966
issued in July 1974 a mandate for all freight cars to begin having the
new consolidated stencils applied. "
Apparently, the 1972 requirement was for the original single panel style, while the 2-panel version was required in 1974. I have never seen a picture of a 2-panel COTS on a car before 1974, but a lot of them didn't get one until several years after 1974. The single panel style does appear in the early 70s, but few older cars seem to have them, which matches the "new or rebuilt" part. On the other hand, that page clearly says "begin having them", so they also weren't required BY July 1, 1974, as some of the sources I've seen said.
In any case, it appears that the 2-panel style was in use in June of 1974, my preferred cutoff date, so I can leave them on cars if I want to. That's good to know, because they're very hard to scrape off of some cars!
