[robnolimit]

I use the 5 degree rule. Yes, having the panhard rod parallel to the axle is Ideal, but with 5 deg is OK. Many of them, including our new C-10 panhard rod kit (3 deg), lean back a bit to allow for clearance of the diff cover.
On the hight of the bar, if you average the hieght of the bar, that is the roll center height. For example, if the axle mount is 12" at ride height, and the chassis mount hieght is 13", then the Roll Center is 12 1/2". For these old pick-ups, the lower the roll center the better.