The Rutland purchased 15 Pullman Standard PS-2 two-bay covered hoppers in 1956. Some of the PS-2s were assigned to specific services/shipments. The cars were numbered 500-514.
503 and 507 were assigned to cheese whey between Ogdensburg, NY and Augusta, ME. Ogdensburg had a cheese factory on the west end of town. That product was trucked to the Ogdensburg yard and loaded there. The whey was used as an additive for animal feed.
504 was assigned to Gassetts at Eastern Magnesia Talc. It was one of two, but the other number is unknown.
Modelling these cars are easy. Buy the Kadee model, which there have been four lettered for the Rutland. Better yet, also order from Tichy Trains the PS-2 decal set as the Kadee painted versions are missing one crucial bit of information, the routing information. That was added when the PS-2s arrived on the property.
You can also buy an undecorated PS-2 car and the Tichy decals. Link to the decals is here.