At 200K mi I just replaced the rear axles and the front flex disc for my 92 400E last night(it actually took 2 days to complete)
The axles weren't that hard at all. The CD manuals say to remove the rear calipers which I did, but I cant really see why I needed to do it. So if you have to do the job, you can probably do it without having to remove the Calipers. You have to lower the exhaust by removing the rubber mounts up to the Cats. If you've removed the axles before to do the hub carrier bearing, they'll slide out pretty easily, if not, you'll need to use an air hammer to nudge the little bugars loose. You do NOT have to open the center diff on the W124 V8's. You simple remove the 8 bolts which hold the axle to the diff and voila. The passenger side was too easy, the drivers side was a bit tricky because of the exhaust. It would have probably been easier except I was trying not to remove the rubber mounts for the Cats. So I button up everything rehung the exhaust and then tackled the front flex disc the next day. Had to remove the exhaust again completely this time don't ya know
(poor @$$ planning)
So anyways, you remove the exhaust from the mainfolds to the muffler, as a single unit just drop it and slide it to the side. You'll need to remove the idler arm (I think) shield on the pass. side to get at the manifold bolts.Support the tranny (with a hydraulic floor jack and a block of wood)and remove the cross member and the tranny mount. Let the tail of the tranny drop a few inches for clearance. Unscrew the drive shaft locking nut just a couple of (2-3)turns. You do NOT have to back the nut all the way out, nor do you want to. The shafts are balanced and must remain in their original alignment to maintain the balance. If you have to take the shaft completely out besure to make alignment marks on the two halves so that when you re assemble them they remain balanced.....shaft------------(center bearing)------------ shaft
Remove the Cats heat shield and then remove the bolts to the flex disc. Wiggle the drive shaft free from the disc with a 3/8's extension. Disengage the the flex disc from the tranny using your favorite "Omniwrench"(hammer, club,mallet, pry bar etc.) That's about it ladies and gents. (caution when reattaching the exhaust to the manifold, use care to take it easy on those bolts and use the see-saw method to tighten them up. ...left side a little right side a little and back and forth, so that you snug the exhaust securely and there are no leaks).
So lets see, I put it all back together last night(9pm-Midnight) in a leisurely 3 hours, so allow maybe 4-5 hours of a Sat. afternoon to do the job in your well rested state. And allow maybe 3 hours to the do the axles if you ever need to do that job. Sorry no picks. Its sort of difficult when you have to getup, clean your hands(change gloves) take pics and then get back into position to do more work. Then repeat the process. Anyway....enjoy