About 2 months ago I was driving down a rough track in my defender 90 when I heard a strange noise underneath the landy. Immediate thought, due to the terrain, was a stone caught either in a brake guard or drum. Shortly afterwards landy was off the road while I removed the TD lump and replaced it with a disco 200tdi. All went well and whilst celebrating the fact I could go up hills without changing down to 3rd, I noticed the sound again. This time it was louder and beginning to sound expensive! Time to start investigating underneath; play in the prop shafts, but that was to be expected. Pulling and pushing on the UJ's did not reveal any apparent fault. Wheel bearing's OK, gearbox and transfer box OK. Starting to point towards the rear diff and serious expense. I even considered putting some very thick oil in the diff to see if that made any difference (that's what my Dad suggested). Trawled through many threads and this one struck a familiar tune:

http://www.landyzone.co.uk/lz/f7/strange-noise-underneath-cant-figure-out-114281.html

Decided to have another look at the UJ's and found this:

Who'd have thought that such a small failure could cause so much noise! Hope this helps someone, the fix is care of the master busterbus: http://www.landyzone.co.uk/lz/f41/uj-renewal-59812.html

looks a tad bit dry in there mate.

I had the same on mine, 1 of the bearings caps contained a few bearings and alot of dust.

I put it down to lack of grease ( not on my behalf, just bought it ) but the way i found out was the slight thump when engaging in any gear ( as the prop takes up the slack ).

Cheap remedy though and worth doing them regularly.

http://www.landyzone.co.uk/lz/1170983-post10.html