Front wheel drive cars are becoming more common because they are fairly compact units. The driveshaft can be eliminated because the transmission and differential unit are constructed as one piece. From the differential, the power is then put through constant velocity joints to axle half shafts that are attached to the wheel hub.

Rear wheel drive units use all components aligned in a straight line. The engine leads to the transmission. The transmission spins a driveshaft that connects to the rear axle or differential unit. The driveshaft contains universal joints to allow for changes in angle due to suspension compression or frame flex under stress. The differential unit transfers power to the axle shafts which are connected to the wheels.