Right. Er...
Well as Dal says we've found the problem. Just wish we'd had the sense to try it to start with, but then if we had, we might not have found the driveshaft was knackered... anyways... the problem? The driver's side tyre was the problem! <_<
It stems, we think, from when the shocks were knackered, and the tyres were taking the bulk of the punishment from bad road surfaces, and worn unevenly. Changed the wheel over for yet another spare, and the problem has gone!
So, the old, original, perfectly fine gearbox will be going back on at some point (probably when I get an MOT & new exhaust in about June!) and I'll have a spare gearbox if anyone wants it then! <_< :lol: