Adapter plates for mounting accessories to a gearbox of a turbine engine are described herein. The adapter plates may be inverted to mount with various equipment, such as a variable frequency generator, oil pump, a fuel pump, a hydraulic pump, an alternator, an electrical generator, and a starter. Gear shafts may comprise splines in a particular form/shape for mating with the gears. The gears may be inverted to expose a desired spline configuration.