One of the three sources of the 100 Series "clunk" - the front differential bushings support and cushion the front diff through acceleration, driveline moment, and shifting from 'D' to 'R.' Over time these bushings wear out and create a clunking sensation when shifting gears or, in extreme cases, when accelerating from a stop.
Replacing the bushings is straight forward especially if using an air hammer/chisel to remove the bushing in the diff cover (41651-60010). One can also replace the diff cover (41108-60011) by removing the front differential assembly (good maintenance item when servicing the gears/re-gearing etc).
