I read that PRR Freight car color became darker and browner over the years. It was more orange in the early years, sort of in the family of red oxide primer but not quite. At least that is what I have been told. Floquil pollyscale made a color called "special oxide red" that some old timers swear was great for early PRR freight car color. I still have a couple of bottles that I am using. It was blamed on the paint manufacturing moving from natural pigments to synthetic pigments. That could have been the case with other RRs also.
And as mentioned above, PRR freight cars, including cabooses (cabins), were never painted tuscan. They were always painted "freight car red"