As above, the clanking/clunking issue is commonly linked to worn bushes or bearings (A-frame, radius arms, UJ's).
I had a recent issue with pressurised diffs - remedied by fitting new Fr & Rr breathers, but this manifested as leaking EP90 at the wheel hubs... still worth checking yours.
Otherwise, take it to bits again, stage by stage, keeping an eye open for any tell-tale signs of where the leak might be occurring (good light will help), then clean everything up and reassemble with a new seal (I'd use a genuine part).
Bit of a pain doing the job again, but other than living with the leak (depending on severity), there's no real alternative.
In terms of play at the flanges, mine are the same, however it seems to be the way with most of the drivetrain on my 90. I guess if both front and rear flanges show similar movement, but it's only the rear that's leaking, then this shouldn't be the cause of your problem... there again, you never can be sure.