I just spoke to Deaver yesterday. They didn't really list the H3 as an application (even though many H3's and Colorado's run them), and when I mentioned that I would run them in a spring-over arrangement...I was met with "we don't have anything that will work". That was followed with a rambling response about spring rates, custom leafs, blah blah...$700 for a pair. Is everyone in California high or what?
If I'm gonna spend $700 on rear springs...it ain't gonna be leafs! So at this point...I'm looking at some stock replacements, or getting some custom springs here locally for about $250 (what they're supposed to cost). I do have some Rancho springs left-over from my kit but, they have relaxed a tad as well. Right now I'm running stockers and my shackles are folded back nearly touching the bumper, and the main leaves have hardly any arch left in them. This is true regardless of the the position (over or under the axle). I'm only wanting a inch or so more height so a new set of stockers might do the trick. I'm not totally against add-a-leafs but, I've never been satisfied with them on past trucks. I can clearly see "bent" leafs in the spring packs right where they are clamped to the axle, so I know they are shot. After the SOA mod...I had to move my axle to the forward hole on the perches to get it centered in the wheel-well. While welding the perches to the axle I was thinking..."why are there 3-holes in them?" I guess I know now.
The flat spring doesn't bother me that much but, the lack of travel at the shackle does. As a leaf wears...it gets flatter and grows longer, and the result is the "reclined" shackle position. This "relaxing" also moves your axle centerline rearward because the front of the spring is rigidly mounted to the frame...so the spring's growth is entirely to the rear. This in turn, translates to the driveshaft yoke being pulled further out of the tailshaft than you might desire. Regardless...leaf springs are not rocket science. I'll come up with something.
BTW these stock GM springs have 12,000 miles on them, and they're junk. So, you're not alone. I suspect its an issue with the tensile strength of the steel...Brazil?...China? Who knows.