if it is a streamlined car, the earliest it could be would be from the 1947 Empire Builder which was pulled by either E7's or E8's for the most part. if it is a heavyweight car, some were repainted in EB Or/Gr when the Oriental Limited return in 1948-51, but that was also pulled by diesels; F-units from what i've seen. some operated as late as the 60's. i have a picture of #1032 Minnesota on the NP Western Star (1966)
the diner behind the Empire Builder pulled by the S2 should be in the #1030-1051 state series of 36 seat dining cars, but painted in Pullman Green w/ gold lettering.
sorry about not posting a reply sooner
today i went up to chico an took a
couple pics of the car its no is 1127
painted the orange impire paint scheme
but does have roller bearing trucks
looks the era of 47-50 or newer send
me a pm an i will send the pics email
or to someone that can post them.