Loud "clunking" noises from under the car can be very disconcerting, but they don't always mean loose or missing parts.
If you have a "TractionLoc" differential, and it is low on lubricant, it will "grind" or seem to make "clunking" noises, most often when you are turning a corner. Check the grease level in your differential and fill it up if it's not full already, and don't forget the special "Limited Slip" treatment that is needed.
Cheers from Dugly