However, dropping a TC will lessen BOTH ends angles almost equally, not just the TC end. Picture it physically. The only thing that will cause a little bit (and I mean a little bit, LOL) is the "tilting" of the entire drivetrain as you drop the TC. But, figure it out, if you drop the TC an inch or so, the actual tilt angle of your entire drivetrain is not much at all. That amount of tilt angle is the only difference in angle you end up with between your driveshaft ends.
That's why, in most cases, you won't get vibration simply from dropping your TC (unless you drop it significantly, like 2 or 3", but doing it that much usually will cause you engine to hit your firewall, so it's unlikely you'd ever go that much. If you did, that's when you usually have to use shims in the rear axle.
Point is, for most Jeeps out there that are not modified to the extreme, all the technical jargon won't matter, most of us will fall under the ""Perfection" is not required. Minor variations in parallelism are acceptable". <img border="0" title="" alt="[Wink]" src="wink.gif" />