It's more of a pain in the butt than you might think. Are you replacing the front flex joint, the rear, or both?
The problem is that the transmission tailshaft and the differential pinion shaft each have a long protruding nipple that slides into the ends of the driveshaft. Therefore it's not a simple matter of unscrewing all those flex joint bolts and simply dropping the driveshaft end. It won't drop and you can't slide the driveshaft forward or rearward enough to disengage. You may have to disconnect the driveshaft center support and that is a pain to access with the exhasut system being right below it. I can't remember the way Idid it last time but I think you get the general picture.
http://bos-engel.com/benz/yokenut.jpg