 Missouri Pacific Railroad upgraded their GP7s with 567BC engines and replaced the standard EMD 2-stack exhaust with a 4-stack "liberated" exhaust, raising their power output to .Illinois Central Railroad rebuilt most of its GP7s with 567BC engines, liberated exhausts, paper air-intake filters, 26-L brakes (their original 6-BL brakes made them operationally incompatible with locomotives fitted with 24-RL brakes).All but the first locomotive rebuilt had their front (short) hood reduced in height for improved crew visibility.