The G-12 and G-8 are low-cost, general service locomotives that General Motors produced from 1955 to 1970. The basic points of the original project aimed to produce a versatile, simple, economical locomotive, adaptable to various gauges, and of different applications, both for service in extensions and trunk lines.

They were built in versions B-B or A1A-A1A, with or without dynamic brakes, and sold to a large number of countries, such as Brazil, Cuba, Mexico, Venezuela, Colombia, Chile, Argentina, New Zealand, Australia, South Africa, Nigeria, Iran, Indonesia, Egypt, etc... They were, until recently, the most popular locomotives in Brazil, and are still in use in all regions of the country. The biggest difference between the G-12 and G-8 is the number of cylinders and the power of the diesel engine, V-12 with 1245 HP and V-8 with 950 HP, respectively.