Yeah,

I have a Makita monster battery driven impact gun and proper impact torx heads. She puts out quite a hefty Nm torque. If that wont open the torx bolts, I have torch welder in my garage.
IŽll get them open for sure

The new (second hand) rear diff assy is said to be LSD version. I do not doubt the seller, as he is quite a Sierra nutter here.
IŽll check it anyways as you described. Thanks.

Cheers