Crabbing

Today was the first day that I drove behind someone else driving my 73 scamp. On the freeway there is a small but noticeable crabbing going on. The front is stock. The rear end was narrowed (so perches moved). 8-3/4. New ss springs. The shock plates needed a sleeve to match the hole size and pin on the leaf spring. It is not snug, maybe 1/16 inch slop. I also needed to place 4 degrees shims to correct the pinion angle. Where do I look to make changes to the alignment of the rear? When going down the road the front left is more left than it should be

Just curious as to how the rear wheels sit in the wheel openings comparing side to side. If your car is dog tracking, one side will be closer to the front of the wheel opening than the other.