Firstly, the driveshaft spacer included in this kit is only for the front driveshaft, and is required due to lowering the front differential and changing its position. A spacer for the main driveshaft is not included. The driveshaft/pinion angle for the main shaft does increase due to the lift, but it's not excessive as the amount of lift added in the rear is fairly mild (around 2.5") and shouldn't cause abnormal amounts of long-term wear.