Looks abit like the Gavin:
http://www.quadratec.com/products/12042_6100.htm
or the RockHard:
http://www.quadratec.com/products/12066_100.htm
Andy is correct, once you have the rear bar on (and suitably braced), the hinge can be welded on.
If your going to copy one, this one is very nice:
http://www.quadratec.com/products/12057_210X_PG.htm
just put the hinge on the left for the KJ.
My personal favorite is a tube bar like this one on the XJ, and I have seen one on a KJ (the one in Qld with the SFA).
http://www.quadratec.com/products/12025_7X00_07_PG.htm
To drool your way through a complete collection of rear bar work, just go here and page down and browse the ones on offer (pages of them):
http://www.quadratec.com/category/Je...s/48/index.htm