By upgrading the G12 with the new 645 series engine, the G22 was born, which was again built in a wide variety of variants for customers in the first, second and third worlds. Using a non-turbocharged engine has increased reliability and simplified maintenance. The locomotives were available with different gauges and with two- and three-axle bogies. The six-axle variants were available with either the “C” model designation with six traction motors or the “4” model designation with the (A1A)(A1A) wheel arrangement. Steam heating was available as an option. In later variants, the modular electronics of the “Dash 2” were installed, these can be recognized by the suffix “-2”. 