Abstract: A four wheel drive system has two overrunning clutch drive assemblies drivably connected to each of the front axle shafts. The rear axle shafts are driven from a standard or limited slip differential. The front axle shafts in a forward drive condition with no slippage are driven at a slower speed than the speed of the rear axle shafts. Therefore, under normal conditions, power is transmitted to the rear wheels of the vehicle and the one way clutch is overdriven by the front axle shafts. The speed at which the front axle shafts are driven is in the range three to four percent less than the speed at which the rear wheel axle shafts are driven. The one-way clutch assembly permits differential drive to the front axle shafts in a turn or when slippage occurs. The front axle shafts transmit drive only when the speed difference between the front and rear axles is overcome.