No springs or shackles. Rubber mounted torsion axles. Yes I have lowered Pin Box as low as it goes, Hitch is raised as high as it goes. 3/4 ton heavy duty truck rides level.
Can't post pictures but can email them if you want to see them, There is a half moon slot on the front of the axle mount flange which bolts the front of the axle flange to the frame. The axle currently is adjusted down so there is about a half inch between the frame and axle flange in the front. I suspect this is for equalizing the load onto both axles for normal ride height.