That's funny!As 10sec.et said but we use angle aluminum. More likely it is out of square with the front end, lots of times after years of adjusting the rears one tire will wind up ahead of the other and out of square with the front. So have a look there. Dana 60's have the tubes from hell, i can't imagine one of them bent. A 9" ford, well, they come bent to save time and aggravation.
I shouldn't much in a perfectly straight line on a prefectly flat surface, but due to surface irregularities and side to side differences due to weight/hieght/body roll it can easily effect how one tire is sitting on the ground in relation to the other.Caster and/or front-to-rear offset can indeed change the drag
I don't see how castor will affect drag.....explain.
If you have much front end lift/rise out of the beams it will also have little to no effect on the roll-out/beams.Front to rear offset (stagger, where one front tire is ahead of the other) is a pretty much a desireable condition where you launch from the rearmost front tire and trip the beam with the foremost front tire. It is such an advantage that NHRA limits us to how much of a stagger (i think it is 1", but heck 2" is close enough for me). And that should have no effect on rolling resistance.