Also, don't forget about the leasing companies that use short line reporting marks. CBRY cars seem to be owned by First Union Rail, FURX. GE has many roads using cars it owns. East Erie Commercial (EEC) was probably the first, 12 miles long but has 5600 cars with its reporting marks. LW is a CIT Group road, with 2700+ cars.
Many times the shortline doesn't own the cars, but lets the leasing company use the reporting marks for a part of the fleet. "Railroad" owned cars get higher per-diem and demurrage rates, so the leasing company gets a better return on investment.