DIY Spring Extender - Rev 1 - Half-a-Puck, PICS

As far as the retention goes, think about what happens when the truck goes over a bump and jumps up. You can easily get enough clearance to let the stop pop out. I would make some thin nuts and put the bolt in the bottom with 271 locktite. I wouldn't worry about them rusting in place. If they are on there that long, it means it worked, and they can always be taken off with a gas wrench.;)