Hy Crabbyappleton and guys, Grigg has describbed the modern inter axle differential operation fairly well. Both axles get power only when the inter axle diff. is locked. The power divider in the 56 through 59 series Chevy tandem trucks functions a little differently. In "normal" operation only the forward axle recieves power, the power divider has two operating levers, the lever farthest to the right shifts the unit between underdrive, "puller", and direct ratios. The lever to the left of the range shift lever is the "declutching" lever, this lever engages drive to the rearmost axle, and is automatically shifted when "puller" ratio is selected by the range shift lever. The declutching lever can engage or disengage the rear axle in all ranges except "puller" range, I hope that clarifies power divider operation in the 56 through 59 series Chevy trucks.
