I currently run Colorado/Canyon add-a-leafs and they work well...but probably not as well as the Speedy spring pack. Traditional add-a-leafs get installed relatively low in the spring pack, and they are there to boost the "overload" capacity of the pack, and they don't really address the H3's big issue...the reverse bending that occurs at the end of the main leafs (by the shackle). This bending problem lets the truck settle even more and also leans the shackles all the way rearward, so they are riding at the end of their usable stroke. The steep shackle angle has as much to do with ride height as the actual spring does. I've never really seen this problem on any other leaf-spung rig...but the H3's are famous for it. Rancho or stock...they all do the same thing, eventually.
The Speedy mod reinforces the main leaf with a FS Chevy leaf, which IMO is the better solution. Either mod will restore your ride-height...but, I think installing the Speedy springs on a brand new set of stock springs would probably prevent them from ever sagging in the first place. It just seems to me like the second leaf on the H3 is just too short to do anything.
