Well I got the diff out from the 12v 164 engine without having to remove the engine from the chassis.
No debris in casing and no signs of damage. Hopefully the bangs and noise was the wheel bearing, 'cos if it was not that, all that is left is the gearbox.
I had to take the gearbox mount off so I could raise the gearbox about an inch to wiggle the diff cover and diff out together. The cover would not come away with the diff in position as it hit the bottom rear rail.
New diff in post from Autolusso. £630 delivered including new seals.

Anyone know the following please.
Torgue settings for left and right driveshaft cover bolts
Torque settings for diff cover bolts
Torque settings for crownwheel

Any thread lock required on any of those.

Thanks
Steve