39 locos were rebuilt from pre-war C59s, while 8 were rebuilt from post-war variants and renumbered to C60 101 to 108. With the spread of electrification, lower axle loads and greater versatility had become more important requirements than sheer pulling power, so an additional trailing axle was included to reduce the heavy axle load of the C59 and allow more widespread use.
A total of forty-nine locomotives were refurbished from earlier models, while eight were revamped from newer variants and renumbered between 101 and 108. As electric trains gained popularity, lighter axle loads and greater flexibility became more vital than sheer strength, so an additional trailing axle was incorporated to reduce the C59's heavy axle load and enable wider usage.