Here is a DIY from DMORRISON. the new axles are the Annular. and the old are the Homokenetic.
http://www.peachparts.com/Wikka/W123RearAxles
the Annular have a row of bolts (6) that connect the axle to the piece that fits into the differential. some call it the stubb, and it stays in the differential.
remove the 6 bolts, and the one in the hub. push axle towards the hub, drop down and pull out. place new axle in hub, connect the 6 bolts.
the Homokenetic axle is all one piece. to replace it the rear cover on the differential has to be removed to get to the "C" clip that holds the the axle in.
remove the bolt in the hub, shove axle towards the Differential to clear the hub splines and remove.
Both axles connect to the differential with the "C" clip. the big advantage to the Annular is simplicity when having to replace one.
Annular seem to cost more than the Homokenetic I`ve noticed when looking up parts.
when pulling them at PNP, the cost is the same, I have found some new one`s a time or two.
Charlie