I t might be useful if I share my experience with this job. My Australian car is a 1981 non-turbo with SLS. The outboard end of the right hand shaft collapsed, so there was lots of clearance for removal. No salt on our roads so the outboard spline tapped out with a bit of broomstick. General approach has been well covered elsewhere on this forum by others. Replacement was a DSS axle shaft from the Pelican. However, after circlipping the inboard end of the shaft in place, I had a lot of trouble obtaining enough distance between the diff and the hub to swing the outboard spline into position. I removed the rear diff mount and jacked the diff up as far as it would go against the underside of the chassis. I disconnected the upper bolt on the hydraulic suspension ram to allow the suspension arm to fall as far as possible. Clearance was still inadequate so I then used two large screwdrivers to force to outboard spline onto the hub back plate,carefully sliding and levering it across the back plate until it slipped into the hub spline. I found that if I rotated the axle shaft there appeared to be "sweet spots" where clearance increased marginally. This was done very patiently in fear of damaging the axle spline but all went well.
Access to the top of the ram warrants a comment. Hydraulic rams on the wagon are different to those on a saloon and access to the top bolt is by removing a carpeted coverplate behind the rear seat which extend from one wheel arch to the other. The coverplate is retained by three self tappers through tabs on the rear edge and these are covered by the lip of the rubber liner of the storage tray. Two further self tappers are located in the middle of the carpet on the cover plate. When the screws are removed, the cover plate can be levered slightly sideways and tilted slightly forward and pulled upwards at the levered end. It is not necessary to remove the wheel arch trim (which I did the first time).
Are there any other suggestions on obtaining the clearance to make axle shaft installation (or removal) easier? Is it ever necessary to lower the rear suspension frame?
Andrew

Hi Andrew - thanks for posting your experience with the process. Have you taken a look at our site's DIY tech articles? There is a guide for the axle replacement for your W123 - please let us know if you have any questions about future repairs; we'd be happy to help out with any info and link you to relevant sources.

https://www.pelicanparts.com/techarticles/Mercedes-W123/105-SUSPEN-Axle_Replacement/105-SUSPEN-Axle_Replacement.htm

Andrew, I had the same issue when changing the axles. To resolve the problem, I lowered the differential as low as possible then inserted the axle ends into the hub. Once they were bolted at the ends, I jacked the differential and bolted it into place.

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Sam

84 300SD 350K+ miles ( Blue Belle )