I purchased a used 2001 Discovery series II with 54,000 on it(My first land Rover purchase). The truck has run great until recently. The truck has a slight vibration at slow speeds and goes away at higher speed. I also have a clunking noise when i shift the truck into reverse and drive and when driving and letting off the gas i get a clunk...I have no idea what this could be..Some people have told me I need to replace the U Joints and others have told me that its the front driveshaft because the front U joints aren't replaceable...Anuy suggestions as to the problem would be greatly appreciated...