I don't like the look of the off the shelf drive shafts to fit Jag diff, plus they are expensive at over £800 !
My cunning plan will probably save me bugger all as the steel cost £200
Bohler M238 DIN 1.2738 pre hardened with approx. 150,000 psi tensile strength
Should look like this when machined, although the splines turned out to be a pain in the arse to figure out and cost me more cash for a form cutter.