How do I get the lift I need without shackles?

YES Rumblefish360! Are you using the 3200 lb rated P3412002's? Or the next higher model # for 3400 lbs?
There actually form my ‘73 Cuda rated @ 3600lbs. Next spring down on the list. I have in waiting the next spring up on the page from the 002-003 springs going in the Duster later. (Lightest S/S spring) The car is currently going on a weight loss diet.