I have my second LX 470..the first was a 2000 without the "Drive Shaft" issue and it was fine.
Then I ordered a new LX 470 in 2005 and now I am on my FOURTH "Drive Shaft" because of the "clunt" that occurs. Lexus has replaced all four and ultimately told me it a manufacuring problem and they did not actually manufacture the area themselves, but used an outside source. Because the car was under warrenty they replaced it. I then bought an extended warrenty to cover the problem if it would recurr and they (after many months of argument and proving to them I am a good customer and after the dealership got behind) replaced it while it was still under the extended warrenty to 100,000 miles. Now, I am on my own and don't have problems for the last 3,000 mile over the 100,000, but I would expect it to recur.
All the best to you.