Freelander 2 (LR2) Diff drone

just went to see a 2013 commercial but the loud droning from the rear put me off.
I also noticed one of the rear tyres was mismatched - the right size but Michelin M&S when the others were Goodyear Wranglers.
Seems like the diff is foobard but could it have damaged anything else? My knowledge is pretty much limited to the FL1 when it comes to final drive.

It could just be the tyres. It quite common for mismatched tyres to show some form of stress distortion "stepping", which can make noise. Our now departed Ford Kuga was getting very droney from the rear at 30 to 50 Mph, which went the moment I swapped the tyres side to side. It had odd tyres on it, having the original Hankook Dynapro's on the rear and Continental Contact SUVs on the front.

A 2013 FL2 should have a better rear diff than the early models.