buick drive shaft???

whats the purpose of having 2 u joints at each end?

 

like this but thats not mine

 

That's a Cardan joint. With a single U joint at an angle, the driveshaft speeds and slow in a revolution, and then the U joint at the other end converts it back to an even rotational motion. I'm guessing high end GM cars got this joint as it halved the U joint angles so there was less driveline vibration.

 

oh... well its hitting my floor and its pissin me off