Did you see this set up, a bit different, but does the same thing, called a Gemini connector. I spoke to Mike at Chassisworks when I bought my G-link rear end set up and they sell just the lower machined part. Requires welding the base to the frame.
http://www.cachassisworks.com/p-1633...ild-steel.aspx
I clipped these photos from the installation instructions.
http://www.cachassisworks.com/Attach.../917055-F1.pdf