Hi Jacek
As pointed out the springs may be under a lot of tension if the center bolt has broken. Here are two photos of how I uncompressed and then reassembled the springs when I restored my HUP.
The funny red and white lines on the springs were so I could be sure to get them assembled back together with all the leafs going back in the same order and not getting mixed from one spring to another.
Go light on painting the leafs too much paint will make it hard to get the bolts through the spring clips and as the paint wears from movement of the springs the leafs will tend to separate.
Also once you have the truck all assembled and have driven it 1000 miles remember to re-tighten the U-bolts, while you are doing that check all the body mount bolts as well. On my HUP I discovered stuff that was tight when first assembled was loose after driving.
Cheers Phil
Cheers Phil