You should play with torsion bar settings while hooked up to an alignment rack, a little change will change the readings ALOT. Used to get torsion bar vehicles in all the time way out of whack, I'd set the bars so the ride height equaled out and sometimes that was all that was needed, that would pull the readings "dead nuts". I don't remember how many I fought with trying to get them aligned, then correct the torsion bar settings, and then I'd be able to get the alignment into spec so much easier, most often I had to raise the left to match the right side.
I always sent them out measuring the same side to side.

I just bought new leafs for my fury last year and put them in. Big difference. I had a choice of 2 or 3 options on number of leaves I can't remember now. I think there were 3 choices on that one. Regular, and 2 heavier duty ones. If I remember right mine had 4 leaves, had a 5 leaf option and a 6 leaf option for police/taxi/fleet/tow package. I stepped up 1 leaf from original and it sits perfectly now. I got tired of chasing leaks in the lines to the air shocks. I now have standard style but heavy duty shocks on the back and it rides so much better, too.
Just age had taken their toll. I had taken the original leaves off back in 07 and had them "re arched" and that didn't last 1 summer and they were sagged out again. My fury is a 78 2 door. So they were past due.