I spent a few hours on boxing day fitting the rebuilt callipers to the diff. I used the same alignment spacers as came off the XJS which worked fine. It took me a couple of attempts to get the steel wire right to ensure the bolts holding the callipers could not vibrate loose.
Those who know these parts well with notice there is a missing component on the callipers! I forgot to order replacement locking washers for the handbrake retaining bolts…..I have added a label to remind myself before the whole assembly gets installed onto the chassis.