Like billy said, that's a buggy leaf or 3/4 eliptical. Been around for a long time. Yes, it works. BUT it also has it's draw backs. Many people have complained about it "unloading" during steep down hills causing a potential "endo".
I tried this setup for awhile and always had a hard time finding a main leaf that was flat enough to lay flat on the frame but soft enough to still droop. It also has a tendancy to make the ass end lift when under hard forward torque situations.
There are still guys using this setup but not as many anymore.
Some people, like myself, have gone to a dual shackle setup. Search for dual shackle, missing link and also revolver shackles. Many of us have had success with this setup, while others didn't like it at all.
It's always hard to get a lot of travel out of the rear of our trucks. Part of the reason the front move so much better than the rear is the front springs are quite a bit closer togeather. The rears are far apart, whic gives better stability, but it takes some of the leverage away. Some guys have moved there rear springs a couple of inches closer togeather on each side. It takes some fab work, but makes a huge differance in flex.
Good luck on what ever you decide to try, just make sure it's safe, it's not just you're butt on the line, it's the family in the other lane too.