1/2" thick steel extended shackles, dont wimp out on the thickness of the plate used to make the shackles as this a support point of the van.
Here is the block under the spring pak ..
When I had the whole van, 9350 lbs, 6 ft in the air came down on the ft driver tire ... ripped the shock mount right off the frame, it came back home draggin the shock ....lol
When I had them reattached I had them welded but good ! The bilstien shock held up, bottomed out & the van wanted more. The bilstien didnt bend, crush or leak. In fact its still on the van 10 yrs later.
Live & learn, if it breaks make it stronger.
ADRENALIN BY THE GALLON ! !