Cut the shock absorber top mount off and removed the old axle. This bit was quite hard work and required a lot of effort. Saying that it was nothing compared to the force required to undo the 14mm halfshaft bolts and the 24mm radius arm supports.
Fitted the radius arms to the good axle (the first time the wrong way around - see picture) and fitted the axle to the car. Looking good it was too.
Removed the entire halfshaft assembly from the old axle and.... bugger! The spines on the halfshafts are different to the others on the new axle. My old ones are 24 spline, whereas the new ones are 10 spline. It turns out that the 10 spine are the weaker (and older) of the two designs.
Two choices then, replace the diff or change the half shafts. The half shafts are completely different (one has a push in driveshaft, one has a circlip). Quickly came to the conclusion that the diff change, however much of a ballache it would be, would be better than messing around inside the swivel balls.
Problem is that the diff needs to come out of the axle on the car, and the best way to get it out is ... remove the axle again.
New axle duly removed again and I swap over the diffs. Fitted the correct halfshaft into the new axle and all looks good, although I am not sure about the correct operation of the diff. It seems that the diff input movement hardly moves the wheel. It'll become clearer when the second halfshaft is fitted, when I can check the operation completely. Quite a productive day, even though I didn't start till 4pm after Emma's birthday party.
This is rapidly turning into a disco build manual. Will return to Locost building as soon as the disco is happy :-))