Gearbox assembly

An engine system comprising:

• a gearbox assembly that includes a housing having plural interconnected gears disposed between an engine side of the housing and an alternator side of the housing, the housing configured to be positioned between a replacement engine that replaces a previous engine of a powered system and a first alternator;
• a rotatable engine coupler connected with the engine side of the housing, the engine coupler configured to engage a rotatable shaft of the replacement engine;
• a rotatable alternator coupler connected with the alternator side of the housing, the alternator coupler configured to engage a rotor of the first alternator,
• wherein the engine coupler is configured to engage the replacement engine and the alternator coupler is configured to engage the first alternator to transfer rotation of the shaft of the replacement engine to rotation of the rotor of the first alternator;
• and
• an auxiliary rotatable shaft projecting from the housing and configured to interconnect with a rotor of one or more of an auxiliary alternator or an auxiliary generator, the auxiliary rotatable shaft coupled with the engine coupler by the interconnected gears in the housing.