The Jag XJS has a beautiful IRS and a Powerlock Diff. They give a great ride and are prety bullet proof. Over here in the UK they are a better choice than solid axles and it was first choice for my '56 F100. The only downside is that the discs are inboard and in some cases they can be difficult to get at for service. They also run four coilovers.
Regards from the UK, Rick