Beano... With the left front being low, you have to figure out if the diagonal end is high. IOW, if the rear is kicked up for whatever reason on one side, it might be helping the opposite front. Maybe not a lot, but it could be a factor. I'm guessing at this, but measure the leaf springs on both ends and compare Left and Right. Crummy illustration but you should get the idea. If these are close then you have to look at the front springs very closely. If one is broken that would probably be obvious, but lets say for whatever reason, a small section of the end of the coil spring broke off... IIRC, cutting half a coil could lower the car 1" on that side. Some people heat up coils to drop their cars, maybe that happened along the way in its life? You can probably measure the distance between the upper control arm and the lower control arm with a common point.
Disregard the rack, But take some measurements from the ground to various points on the upper and lower control arms. Maybe something will be obvious when you're under there.