I left BS in mid-1974, and the City Rock didn't run much longer afterwards as a separate train. Not sure when it got merged with the EPT/BS/whatever turn. Worked a couple of EPTs out of pool 2 after 1974, with 2700s (re-numbered 1400s) but don't recall how much rock was in the trains. I figured out later that I goofed a leakage test with that 2700 because its DS-24 brake valve had the WABCo pressure maintaining feature, which used a separate cut-out cock for checking BP leakage rather than a brake valve handle position like the SP's modification.

There were several rock outfits: one up near the 18th St yard (PCA -Pacific Coast Aggregates- as I recall), one on Quint St (Rhodes and Jameson), one out near the WP ferry slip, and a couple of others which were smaller.