For years this argument just amazes me. The parallel driveline guys set up there leaf spring suspension in their beautiful hemi whatever and argue nonstop about that is the way it needs to be because the ends rotate at different speeds yet never once thinking about how there drivetrain is NOT parallel on the 20 mile trip to the car show. Their drivetrain may never ever see that parellel unless they are at the track and have made a nice clean pass.

I used leaf spring as an example as to how silly this arguement is. There is no way the driveline could ever be parallel under normal driving conditions except at the track. When you get to 3 and 4 link suspensions, the angles get smaller to the point of there may only be 1 degree difference in a car and because the car has a suspension that constantly changes, there is no way you can make the arguement that those of us that set up pinion angle off the driveshaft are wrong.

But for us driveshaft angle guys, we can argue that the parallel guys are wrong if they set up there drivelines with a positive angle at the rear joint. And this is the reason why we say not to use the parallel method.