Thank you again,

I will not try to open or dismantle the rear diff assy. Definitely not

I have now agreed to buy a second hand diff box from a Finnish FB Sierra group member here.
Should be a correct one with correct ratio and correct type flanges for the props.

Is there anything out of the ordinary when I remove the old under the car? I havenīt done this type of rear diff removal before. Just Atlas type with my summer banger Capri.

Just jack up the rear diff and open bolts and nuts from prop shafts and last the rear diff assys mount?

Cheers!