SLSF 500-514, 557-572, 598-618, EMD GP7, with steam generators SLSF 515-549, 555-556, 573-597, 619-632, w/o steam generators The EMD GP7's were the Frisco's largest class of locomotives until the later GP38/GP38-2 series. The GP7's proved to be very successful, as they did for almost every railroad that bought them. The Frisco probably over-bought units equipped with s/g systems. Eventually, many of them had their s/g equipment removed. Note these early diagrams state that the GP7's can m/u only with other GP7's. That was because the GP7's were equipped with 6BL brakes, while the other Frisco EMD and ALCo cab units the GP7's would likely m/u with used the 24RL brake, which was not compatible with the GP7 brake. Anybody know why the SLSF did that? Later, the GP7 brake systems were modified, and they went on to m/u quite successfully with virtually anything in the fleet. Ken
