If your truck has around 100,000 miles or more and has not had the swivel balls and bearing service it is probably time to do it. It is similar to a LR service. A lot of Land Rovers are sold in this country about the time the owner realizes they have to do this service. The Axle Nuts are unique and need a special tool. My '85 needed updated nuts to mate with the MB claw socket wrench I purchased. I would recommend 4 new nuts and 2 lockrings. Buy all MB seals with the exception of the axle seals which were around $33 US each and locally sourced seals will likely work there. All of the bearings can be sourced through bearing supply houses and are 1/2 the price of those through the MB parts system. I used Timken and NTN bearings and I think the NTNs are of outstanding quality. Look at Dave Gomes' tech articles on the Clubgwagen site and his parts list. Both are excellent and will provide a guide for the work ahead. You or your mechanic need the claw wrench, a bearing press and puller, and a selection of drifts and punches. It is a bit time consuming but interesting to do. Do it right and you probably will not have to do it again for 100,000 more miles or so if you check adjustment on the wheel bearings from time to time. There are a lot of people here who have experiance with this and can help with questions. I found a wheel bearing that was very bad but I caught the problem in time. It would have been a very expensive project if that had come apart in there.
-Dai