Don't use little pieces of leaves as a stacked block, that's asking for it to be weak and/or slip apart on the highway or under abuse off-road. I've seen a dodge lifted that way, and it was sketchy sketchy sketchy, and not street legal. You can mix and match leaves from the spare packs and your current packs, to stiffen the ride up and maybe get another inch or so out of it, I'm not sure what you'll end up with. Personally, I've always swapped leaf packs as a whole assembly and buy new - I've broken old leaves more than once, once time on my old ranger I snapped both sides at the same time, kinda sucks when your rear axle tries to walk up to the front of the truck going down the road with a full load of firewood.
