I was looking around at drive shafts and the flexible coupling they use. found some interesting things. Below is a link to a very interesting new constant velocity joint. On the right hand side you will see a down loadable video explaining the Thompson coupling. After viewing this I sure would like to have a drive shaft built up with these joints.

http://cvcoupling.com/index.php?opti...d=36&Itemid=58

Here are some interesting animation of a UJ and a CVJ.