When you add wedges between the leafs & the axle tubes, the centering bolt's head will not be long enough to reach through the wedge & into the hole on the leaf spring pads.
GM lists 4 different lengths of centering bolts. 1/2T 2 wheel drives use the shortest. Get the next longer ones. Cheap from the dealership. $5.00?
Get a nut & crank it down to the head of the bolt. Bit of red Loc-Tite.
Round off the shoulders of the nut on a grinder to the size of the head.
Remove the factory ones & replace with the new, modded ones.
2nd pic from the top is what you're aiming for, as that's good as it gets for these trucks.
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