The stock diff is fairly stout. But it is susceptible to damage if beaten on regularly and the fluid is not maintained. Could be a bearing.
The diff bushing is very prone to failure (I bet yours has), but the result is maybe noticing a bit more slack in the drivetrain, not loud clanking in reverse.
There is also a rear axle click issue that can be annoying, but I certainly wouldn't describe it as "loud clanking" (
FIXED: Rear axle click clunk noise).