Disco 2 Auto Gearbox lockup

Picked up a very nice V8 Es 2001 Auto today which needs a few bits and pieces sorted but generally in very good condition. Drove is back on the motorway and it cruised very nicely but I thought it felt a bit busy with the revs being higher than I remember.
It's been a few years since we had a Disco so I'm not sure my memory is as good as it was but I seem to recall the box slurred into an overdrive gear or lockup over 50 mph or so. This vehicle didn't do that. Is there anything I can check to confirm all is ok as the vehicle has a short warranty and it would be good to get any faults sorted asap. Cheers

just test drives and state of the oil ,black means clutches are about finished, brown just been in too long ,boxes often dont get the oil changed enough mine fresh d2 played up till i changed the oil a couple of times

my td5 locks up at about 52 mph I would give the box a filter and oil change with quality oil