Backlash Clunking Noise

A loud clunk noise upon acceleration and deceleration could be caused by the following components (or in combination):
^ Differential pinion mate gear shaft-to-differential case bore.
^ Axle shaft splines-to-differential side gear splines.
^ Differential side gear hub-to-differential case counter-bore.
^ Differential side gears-to-pinion gears.
^ Worn thrust washers.
^ Excessive ring gear backlash.

Measure the clearances, inspect the components and replace as required (or, if applicable, adjust to specifications).