I had the same problem. I was told I probably had too short leaf springs. Since I paid good $ for 6 leaf 'xhd' springs off ebay last year, I decided to keep them and extend my rear hangers foreward. Another strategy is to shim them if you only need a little bit more angle. You can also shim the front hangers but then you're lengthening the wheelbase.

I got a used set of hangers, cut them and welded in some plate, moving the rear shackle upper pivot foreward a few inches. The new longer hangers are gonna touch the trunk floor to avoid getting too much leverage on the two bolts that hold them on (72 demon). I have to shave the tops outboard sides because the trunk floor is bead rolled (probably stamped but you know what I mean) right in that spot.

Anyway,
Good luck