caster angle question
 

caster angle is set around 2-4 degrees positive, which means the "pivot line" has the lower balljoint/kingpin forward of the upper, is that correct? So when increasing positive caster using shims you would actually turn the pinion downward?

Re: caster angle question
 

Yes. The pinion angle shouldn't matter with a double cardan joint in your shaft

Re: caster angle question
 

You shouldn't need any more than 3-4 degrees with a leaf spring front end, unless you are running huge tires

Re: caster angle question
 

2-4 degrees caster is fine, and I'm pretty sure your pinion angle does matter with a double cardan joint. Pinion angle needs to match the driveshaft angle, or within 3-5 degrees. And pinion angle takes priority over caster angle.

Re: caster angle question
 

Front driveshaft u joint angle is not more important than drivability. Get the right caster. I run 6 degrees.