As shown in the picture linked by OPRRMS the Santa Fe regularly assigned TEN big 6 - axle freight engines ( Alco RSD-15 & EMD SD-24 ) to the York Canyon train. Union Pacific would order their SD-45's with 6 brake cylinders & 12 brake shoes per truck partly for their use on the joint train with Rio Grande. These were HEAVY trains, limited to mainline trackage only on Santa Fe; other trains would run around them using the sidings. The Rio Grande / U.P. power would often be used on San Bernadino to Barstow turns while the coal was being off - loaded at Kaiser, making them common sights across Cajon Pass. Remember the Sunnyside trains used Santa Fe crews West of Barstow.