The present invention relates to electric drivetrain kits for converting all-terrain vehicles into hybrid or electric vehicles. In exemplary embodiments, a conversion kit replaces an existing standard single motor and transmission drive system with a dual set-up including a motor for each rear wheel and a split transmission that houses two sets of gear reduction components in a single housing or an all-wheel configuration with two transmission sets (front and rear). Dual output shafts in each transmission set drive the wheels independently to provide the torque needed as required and demanded by each wheel. System electronics send signals to the motors and other components to manage the system and independently control each wheel.