8.75 diff - metal in oil (pictures). Is it ruined?

I agree, I went to someone respected in the UK for building pro mod cars, with his own 5 second car.
Build a lot of UK top race vehicles, he inspected it and suggested the metal flakes might be from the shortened rear axle...

... The person that shortend the rear axle advises this is not possible as it was cut in a special way, with a water jet directing metal away from the casing...

I think the sure grip is not ruined but nearly ruined.

I don't mind taking it to bits, I just to not want to have a box of bolts and cogs I can't do anything with having lost all the pre-load settings etc. If I can take this to bits without causing a rebuild issue then fine!