Yes the valve body / block is integral to the transmission but can be viewed with the transmission sump removed but without removing it you can't really test it.
The valve body pistons fail gradually providing low pressure to the torque converter which then burns out the clutch in the torque converter sending metallic debris into the transmission killing that.
This will normally happen around the 100k + mark, vibration under low revs up an incline is normally a warning of impending TC failure.
Then the transmission is rebuilt and TC replaced but the valve body issue is not addressed which causes the clutch to fail again only quicker.
The valve bodies can have the piston bores reamed out and fitted with new pistons by sonnax i think it is.
http://www.rangerovers.net/forum/6-...8-sonnaxification-gm-5l40-e-valve-bodies.html
Anything you can find from Bemble or RRPhil (same person) across the net will be good advice.
The transmission could be functioning fine, the only way you would know would be if there is a receipt to tell you it has already been carried out.
Apart from that, gear changes should be smooth, not delayed in either forward or reverse or hanging onto gears too long, and no banging into gears, if it is the same as my 04 4.4 you shouldn't really know it is changing gear apart from an engine tone change.