For a couple of months now we've had a sporadic bad vibration, only ever related to road speed rather than engine speed and got so bad occasionally the CD player wouldn't.
We'd replaced a CV joint, UJ on rear of front prop-shaft, generally tidied up, greased up and checked everything we and a local garage and 'Landrover nut' could think of and couldn't trace the source ... but I found it today.
I'd reasoned that as we'd replaced one front propshaft UJ, it would have been likely that the other was 'going' and might conceivably need replacing, but we'd already looked and so had others, but I thought today, up on the car ramps and have a good old tinker and see what I could see.
Two of the bolts holding the front UJ flange onto the diff driveshaft was loose, so tightened 'em up. Didn't cure the vibration, but what it did do was show that the front UJ was also nackered with two of the couples as dry as a bone. I reckon the loose nut/bolt had been 'masking' the loose UJ making it look like play in the diff ..... and a blocked grease nipple can't have helped.
Replaced UJ and all bolts/nuts and jobs a good 'un. Went for a spin and was amazed at how feckin' noisy my tyres are ... ;)
CD's now also don't seem to skip, 'cept over the ditches ... ;)