Auto Classics : Jaguar XJS Buying Guide

Another buying guide:

https://www.autoclassics.com/posts/buyer-guides/jaguar-xjs-buying-guide

I read this interesting remark in this article:

"The smoother Model 400 three-speed General Motors unit (fitted from 1977) and four-speed GM400 (from 1993-on) can often produce a knocking noise from the gearbox mount, a common problem after the spring holding the gearbox in place collapses. "

Perhaps it's the same issue "knocking noise" I'm hearing as well? I tend to believe it might be related to the U-joints:

https://erwinxjs.blogspot.com/2017/04/u-joint-diagnostics-propshaft-xjs.html

https://erwinxjs.blogspot.com/2017/04/u-joints-propshaft-replacement-attempt_29.html

Clearly I first need to build up the car before looking into this again, sigh.