Just an FYI, As I make progress on the overhaul of my '95 XJS 4.0 convertible I do discover alternative parts from time to time.
The latest: JLM1388 half shaft U Joint crosses to GKN (GMB) 426 26002 288, I've seen prices on these from low $20,00 range to over $40.00 US and NAPA P331 for $13.99. Both appear to be of good quality (P331 is made in China). The MSRP for the Jaguar JLM1388 is over $230.00 US which is much more than a gouge!