Uneven ride height on the vehicle can be caused by leaking air springs.Google+
Car Problem Reports
Land Rover Discovery Leaking Air Springs May Cause Uneven Ride Height
Land Rover Discovery Problem
Average Mileage: 104,333 mi (101,000 mi - 110,000 mi)
Visitor, 2001 Land Rover Discovery, 102,000 mi
Air bag on passenger side failed after wearing out. Ordered new replacement air bags & replaced them. Quite easy actually... Followed online directions & ordered new air bags off of ebay.
Visitor, 2001 Land Rover Discovery, 101,000 mi
Replaced rear airsprings with bilstein aftermarket parts, saved a bunch.