Alpha Auxiliary Transmission (PP) [D-Series & GPV] 1.3

This mod provides an auxiliary transmission, sometimes known as a "brownie box" or a rangebox, with 2 speeds for the D-Series and GPV. Provided are an overdrive and underdrive box as well as a customizable auxiliary box. All three boxes have 2 wheel drive and 4 wheel drive versions that work in any transmission gear. The overdrive box can be used to reduce engine rpm thus providing greater vehicle speed. This is useful for transmissions without an overdrive gear(s) or offroad vehicles with very short differential gearing. The underdrive box does the opposite: it increases rpm for a given vehicle speed thereby increasing torque at the wheels, perfect for offroad vehicles or heavy towing. This is exactly what a high/low transfercase does but allows you to reduce any transmission gear in both 2 wheel drive and 4 wheel drive. This mod can be used with high/low transfer cases to compound gear reduction.

Please make sure to used the 2WD versions for vehicles with RWD transfer cases and the 4WD versions with 4WD transfer cases. Not tested or intended for AWD vehicles.

This is my first attempt at modding, so any advice or suggestions are appreciated.