Gearbox failure/ rear brake disc:calipers
 

The fault with the MAF producing an incorrect load value and resulting in mismanagement of the gearbox and its subsequent failure by the engine ECU and gearbox ECU seem to be mainly in 1999-2001 3.7 quattros. It doesn't seem to happen in D3s - I suspect some recoding of the software to run these systems has been done at the design stage to make a faulty MAF incapable of damaging the gearbox.

It isn't a coincidence that many people go to the dealers with a gearbox that has dropped into 'safe mode' and are told that in addition to a new gearbox they also need a new MAF.

As one would expect all automatic gearboxes will be put at risk by increasing mileage/time without gearbox oil (at least) or gearbox oil and filter (optimal) changes. This won't however save you if you have the MAF problem in a susceptible car.

Going back to the rear brakes, the 1999 3.7Q FL set up which I measured had 22mm thickness and 269mm diameter discs.
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The rear calipers were Lucas/Girling 343812 (Audi 4DO 615423E) on the left
and Lucas/Girling 343813 (Audi 4DO 615 424E) on the right.

What do u guys mean with MAF sensor? Mass air flow or are u meaning something else entirely?...

Exactly that... They get different names from different manufacturers, but the same thing.

So if I buy an S8 should I play it safe & buy a new MAF sensor just incase?

not necessarily but certainly do regular scans with VAGCom to check for faults +++