of the offset 70000 series gondolas renumbered to the 80000 series in 1956 for the standard gauge conversion, and had the "Monarch rock service only" stenciled on them. I imagine the 40 yr rule had them gone in 1962 though....
Corey,
There was no such thing as a "40-Year Rule" in 1962 (it was phased in starting in 1973), and it would only apply to cars used in interchange. Cars in dedicated on-line service would not be affected.
Now I could point out that the CF&I mill at Minnequa was served by its own switching railroad, the Colorado & Wyoming, but two railroads could (and still can) agree to interchange equipment that was otherwise banned from _unrestricted_ interchange.
