there are several drawings about this with explanations,basicly there needs to be and angle and a matched angle at the other end to eliminate the vibration,I will try to find the drawing for ya.at the factory they can offset the pinion to any place they want so that's not why they are offset.more I think for driver comfort and making room for shifter linkages steering boxes,weight bias etc.when I built my pro figure eight car I thought the same thing but when I was moving things around on the scales my pop's had a few questions about how I was doing it and pointed me in the right direction about that subject.I can't seem to find the drawing but it's posted here on fabo somewhere
so the small block im putting in is going to be a 4 speed the car is a 66 dart my question to one of the last threads is how does offseting the trans from the rear end eliminate vibration rational thinking would say it would cause vibration.