I may be able to help out with some of the appropriate models
to model correct freight cars from the early eighties to the incorporation
into CSX. 
    To start with, the model(Life Like) that you have listed for boxcar
#2615 is incorrect. This model is a good representation of a car that was
rostered by PC, Conrail and Western Pacific. However, the model is
incorrect for any RF&P boxcar. The model that you want to use here would be
either the 50' single or double door smoothside boxcar by Front Range or
McKean(both out of production). The models would require some kitbashing of
the doors but has the correct roof, ends, and sides. The real cars are
numbered in the 2201-2300, and 2500-2650 series. They are 50' smooth sided
cars with (2) 8' double plug doors on each side that are centered on the
car. This is important as the model of the double door car is a little bit
different and is correct for another series that I will explain below.
    The next series, is the 2401-4500 series. These cars are similar to the
cars mentioned above except for 2 things. These cars have a 9' sliding door
and a 7' plug door on each side. The uniqness here is that the main 9'
sliding door is not centered on the side of the car. Both doors are offset
to the right a couple of feet. The Front Range/McKean 50' double door car
is correct and includes the offset for this car.
    I have to go now. I do not have a lot of pictures of freight equipment
for the RF&P, but I have enough to cover the different type of cars for the
RF&P through the eighties. These include covered hoppers, gondolas, pig
flats, auto racks and more boxcars and some MofW equipment. I also remember
much of the equipment they had (I only wish I was into photographing trains
in high school). If you can get your hands on any equipment registers from
the eighties or ninties, this will provide you information on any series of
freight cars owned by the RF&P or any other railroad.
    If you have any questions about freight cars, feel free to drop me some
email at dswift@timesnet.net