My 2006 AWD LTD 500 has about 52000 miles on it; a slight rattle/clunking noise is intermittently heard on driver’s side in engine compartment. Took it in to dealer who says motor mount is cracked and front stabilizer bar joints are worn and both need replacing. Car has only been driven on highways or for short trips (3-4 miles) and has had no impacts nor been driven over rough roads or run over any potholes or such. Should the motor mount be damaged? At 52K miles?? Never heard of such a thing. Ditto, the stabilizer bar joints: worn out in under 60K miles? What can I do about this? Who seek relief from? Ford warranty is, of course, over, and supplemental warrenty will only cover motor mount replacement but not stab bar. Are these parts routinely wearing out at such an early date that repair shops can reap the rewards???
It sounds like your only cost issue are the stabilizer links and the rest is covered by warranty.
Stabilizer links can certainly wear out that fast, and I’d say its becoming increasingly common as roads get to be in worse and worse condition - they take a pounding with potholes. With my luck, the longest I’ve seen them last is about 90,000 miles. I’ve had some last me just 20,000 miles.
Here’s my advice - the dealer is likely a high cost for that repair, and this should not be an expensive repair. For ~$22 each you can get Moog sway bar links from Rockauto - Moog is the ONLY brand I’ve ever tried so far that I haven’t had to redo the work later. Not only that, but they actually thought (unlike most manufacturers) and put wrench flats on the parts, so if/when you replace struts/mounts, you’re likely to be able to get the link off easily - other brands I’ve found don’t think it through at all - take Toyota’s OEM for my Camry, for example - they put a ~6 (?) mm allen socket there to do the same job, and that socket will strip out almost every time you try to put force through it.
Replacing both sides should cost about 1 hour of labor, tops, so you shouldn’t be talking much over $110 for the total repair with quality parts.
6 year old vehicles develop noises, a fact of mechanical life.
You could choose not to repair, but…
Since you seem concerned about noises the dealer is going in the direction of ‘‘showroom new’’ condition when attempting to eliminate the noises.
Have them show you the motor mount ‘‘crack’’ and the sway links.
Strongly wiggle the sway bar ends to help you decide to repair or just live with it. Those rubber ends dry and harden with time…6 years regardless of miles…and may not be all that bad, just noisy now.
Rev the engine to see where, in the tourque stress, is the importance of this one.
Because of tourque stress you might want this one replaced now.
Common ?
no.
Thank you both for your helpful comments. I decided to go ahead with both repairs. The service shop did show me the (very small but noticeable) crack in the motor mount, and my service mgr said they get about 2-3 a month on the Five Hundreds they service. I had to pay the deductible ($100) for the repair which was done on the extended warranty. I still think this is absurd; I have never heard of a motor mount cracking or in any way damaged in under a couple hundred thousand miles! Shoddy goods, IMHO. And, I take the news of the wear on the sway bar links in the same vein. Virginia roads are not smooth, to be sure, but I have owned half a dozen cars over the years that I have driven in this state, and several overseas on far worse roads, most to over 100K miles, and never had such a problem with any of them. Fords are not really built that tough.
@HMJ -
If it makes you feel any better, we used to have a Toyota Camry that needed 2 of its motor mounts changed at around 35,000 miles, and our cost was well over yours. 
For the record, I firmly believe cars have never been as reliable as they are now, and I do believe that Fords are pretty darned reliable in general. From my experience, I’ve seen problems becoming more and more consistent across all brands - my Toyotas and my Fords have both had sway bar link issues. Not surprising, though - I wouldn’t be the least bit surprised if they used the same supplier.