This looks like the right thread to report my experience. Replaced the right rear axle halfshaft about 18 months ago. Bought a DSS shaft from Pelican (local Merc supplier said no half shafts in stock in Australia and that it would cost about A$1000 to obtain one from Singapore). Shaft was difficult to fit. I had to unbolt the diff, jack it up, tilt it sideways a bit and unbolt the hydraulic ram from the rear suspension arm to get enough clearance and it was still very tight. I did not unbolt the tailshaft. I had to lever out on the hub bearing area to slide the spline across the backplate. On the inboard end, the original spring clip/spacer fitted perfectly inside the diff -no backlash. Following comments on this forum, I removed and threadlocked the Allen key headed bolts at the inner end. Car has now done about 15,000 km, mainly country miles,with no problems (apart from a very slight diff whine probably related to the original CV failure).