[Dominik]

The point you guys raised is the weld, and Peter B, while building a fantastic replica, used E-type wishbones which came at the correct length.

The trailing arm, as used for XJ6 is not needed. It is rather detrimental if mounted in rose jointed assemblies. The original rubber mount compensates for change in length under suspension movement. If mounted rigid, it may actually break something - like the weld...

Remember, the XJ rear suspension is mounted in a cage - in rubber.

As a side note: I wouldn't be surprised that load in cornering actually assist turn into corners with this Jaguar design (the Porsche 928 followed a similar idea).

It does not apply for a solid mounted differential like we have. The Watt's linkage is a good idea.