Yours will be the third recent instance I am aware of involving the easy separation of the front and rear sections of a W124 driveshaft. Your retainer nut was too loose. The rubber sleeve protects the splines on the shaft. The center bearing is usually pressed off, but if you are patient and careful, you can tap it off with a hammer and a brass drift. There is a special wrench for these nuts, but I have had good luck using a large adjustable wrench.
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.