An old member here named Fisherman did something to his factory leaf springs that made a huge difference. He pulled apart each spring pack and painted slip plate on each leaf. It polishes itself as it moves and creates a very slippery surface. His truck rode like a Cadillac. It only got better as it wore in.

On my recent wagoneer build on IFSJA, I put slip plate on all the window lift arm pegs, in the slots under each window including the tailgate and anywhere it would help. The previously stiff windows rolled up and down way easier after putting that stuff on the metal to metal parts. I see a lot of comments on wanting to make the suspension ride softer.
You don't have to remove any leafs either. It really works well. I'm just mentioning it because I am seeing a lot of comments on stiff suspension as I am trying to catch up with the ten year absence I am guilty of.
Fisherman also pegged restoring hard brittle weatherstripping rubber with long term soaking in 303 protectant. He has a few great ideas up his sleeve. He deserves all the credit for those ideas.

Give the spring pack mod a try. It can be done in a weekend and the results are something else. Be sure to follow the directions.

https://www.slipplate.com/product/sl...hite-lubricant