You are looking at an Atlas {50005251} FMC 5077 DD Boxcar CP< Camino Placerville & Lake Tahoe #7703 (Scale=N) Part#150-50005251. Picture may show another road number.
This is FMC’s entry into the Plate B IPD (Incentive Per Diem) box car era. The design was intended to be the “most universal”, interchangeable on most common railroad clearances. The cars were available with and without end-of-car cushioning, and were offered in several door configurations.