Power Flow

Operation
In all drive range positions input torque is transmitted to the transfer case gear train through the transfer case input gear.
In 2HI range, torque is transmitted from the input gear to the range shift hub and mainshaft. Torque flow continues through the slip yoke which is splined to the mainshaft, and finally to the rear propeller shaft and axle. In 2HI range, the mode synchronizer remains in the neutral position and does not lock the drive sprocket to the mainshaft. As a result, torque is not transferred to the driven sprocket.

In 4HI range, torque from the input gear is transmitted to the mainshaft in exactly the same fashion as in the 2HI range. However, in 4HI position, the mode synchronizer sleeve is shifted into engagement with the clutch teeth of the drive sprocket. This locks the drive sprocket to the mainshaft through the synchronizer. Torque is then transmitted through the drive sprocket to the driven sprocket by the connecting drive chain. Since the front output shaft is splined to the driven sprocket, torque flows through the output shaft to the front propeller shaft and axle resulting in high range four-wheel drive.

In the 4LO range, the path of torque through the transfer case is exactly the same as in the 4HI range but with one major difference.
In the 4LO range, the range shift hub is shifted into engagement with the planetary carrier. This causes the input gear to rotate the planetary pinions inside the annulus gear causing the planetary carrier, range shift hub, and mainshaft to rotate at a gear reduction ratio of 2.72:1.