Any mechanics or Mustang owners...

My wife has an '05 Mustang (V6), with 50K miles. It developed a rotational tapping sound in the rear end. She took it to the dealer, who charged her $59 to diagnose the problem. Their "diagnosis" is that it might be the U-joint, but until they replace it, thet won't know if it might also be the differential. Problem is, they say they have to replace the entire driveshaft with the U-joint, as it's all one piece. They want $600-700 for the repair.

Does this seem right? Does anyone have any expience with this? I've replaced U-joints before (about 25 years ago), but never heard of needing to replace the driveshaft too.

Recommendations on a transmission shop?

Not impressed with Ford quality