Which condition is indicated by excessive noise from the rear axle during acceleration?

Excessive noise from the rear axle during acceleration is often indicative of worn axle splines. When the splines that connect the axle shaft to the differential become worn, they can lead to poor engagement, resulting in noise and vibrations as the power is transferred from the driveshaft to the axle. This occurs because the worn splines may not fit together securely, causing slippage and excessive movement within the axle assembly. The noise typically manifests as clunking or grinding, particularly noticeable under acceleration when there is a higher load on the axle.

The other conditions, such as insufficient or excessive backlash and defective axle bearings, may also produce noise but usually under different circumstances or during different types of load conditions. For instance, insufficient backlash could lead to binding or gear whine under specific conditions, while excessive backlash may cause a clattering noise during deceleration or when backing up, rather than during acceleration. Defective axle bearings can create a grinding noise that's present continuously rather than being specifically associated with acceleration, pointing to a more general wear issue rather than a direct consequence of spline wear.