The ACF Flexi-Flow hoppers were used by PC and Conrail primarily on the Boston Line until about 92/93 when the unloading track was removed from the center of Framingham where the new station now sits. Since that time, Conrail sold the cars to various private owners and spread to the four winds after the mid 1990's.
Well yesterday, I saw several of these cars on the Walpole/Norwood local freshly painted in a light gray and mixed in with several PD3000 hoppers. This is the first time I have seen these cars on the Boston Line in over 20 years. Wish I had my camera!