[Skyhammer]

The recall was for a different issue. Some of the drive lines did not pass the hardness test at the rear of the drive line, which may have caused a failure in the drive line.It was a safety issue, thus was a recall.
This issue is for clunk/think some people have. It causes the bearing in the front of the drive line, or middle of the drive line(depending upon which type of drive line you have), to wear out prematurely.
If you notice in the TSB, Toyota says this will not necessarily cure the issue, but will reduce the occurrence.
Toyota hasn't said what the problem with the drive line is, but it could be that some drive lines are not balanced properly. The TSB did say that they have changed something on the drive line and that newer Tundras have the new drive line(see vin #'s affected).