Here is the Pro-G IRS from Heidts. The system starts with a Ford 9-inch-based centersection that uses CV joints to transfer the power out to the wheels. Since it is a 9-inch-based unit, it uses a drop-out centersection so gear swaps are much easier than a 12-bolt Chevy style. The control arms are made from DOM tubing, and all the other brackets are constructed out of good quality steel. The setup is true bolt-in installation, with only a few holes needing to be drilled. It comes complete, but disassembled with multiple spring and shock combinations available. It retails for $7,999.95.