Anyone know of a source for these little plastic/rubber clips that go on the leaf spring rebound clips? Thanks.

 

Might want to give a call to a well stocked driveline shop that rebuilds leaf springs to see what they might have. If that doesn't work, I'd consider using some urethane seam sealer primarily used to install windshields or fill body seams. Tubes of the urethane can be purchased from paint shops or on eBay.

 

When adding leafs I cut the right angle, straighten them (straight up) and weld. Rockcrawlers open them up intentionally so the leafs can fan out more at full droop. They don't do a lot and don't need to wrap around the pack.

But if you have a tool to actually replace them and replace that countersunk rivet, I'm VERY impressed and I want to know what you use.