Haul truck with modular drive system

A method of retrofitting a device comprising an engine, a plurality of electrical components, and a transmission connected to the engine, the method comprising:

• removing the transmission;
• and
• connecting a drive system to the engine, the drive system comprising a plurality of modules, wherein:
• each of the plurality of modules is directly connected to at least one other module of the plurality of modules,
• each of the plurality of modules is interchangeable with another of the plurality of modules,
• each of the plurality of modules includes one or more switches for controlling a mode of operation of each of the plurality of modules, and
• the one or more switches of each of the plurality of modules are set to control an electrical interface between the drive system and the plurality of electrical components.