This subject came up in RGS site, and I was able to offer the following data of expectation of foreign cars on line:: C&S cars were used on RGS per the conductor record books.
In answer to recent posts which questioned if RGS leased box cars from the D&RGW. Cars were used in interline service and were not considered leased but on per-diem charges and the traffic meant revenue movement to or from the D&RGW in most cases.
A 1923 roster made for insurance coverage only list 6 box cars: 1505,1524,1564,1672,1717,1744; 2 flats: 593,625; 1 coal: 1283, rest are service, passenger business, for a total value of $34,550. But the insurance policy also covered $19,600 worth of value of foreign rolling stock estimated to be 2 Bag/Mail/Exp, 30 box and other cars, 2 coaches, 1 coach/mail, 2 exp/bagg, 2 Loco & tender, 1 Chair car. The similar 1931 roster had no revenue freight cars, listing Passenger and service cars for a total value of $42,500 and $14,000 of foreign cars being the same 30 box and other, 3 tanks, 1 coach, 1 exp/bagg, 1 Loco.[daily NML Interchange] I see no sign of C&S car
being owned by RGS in this time frame. The 1938 roster still shows none. PRR