[68Timber]

Rebuild your shackles front and rear with new bushings and hardware. The bolts and sleeves rust together and bind up. Also the rear bushing (in the frame) on the front leaf springs could be egged out or torn and you can’t see to tell without disassembly. Poly bushings work well. You may have already done this but if not I’d start there before swapping springs.

Edit to add, I left out the stock springs. Rebuild them too while you’ve got it apart. Energy Suspension sells kits for all this and they work.