I've never seen a kit. What I did was cut out the tunnel and ground everything off. I then welded up all of the seams and made a new tunnel. I made a template and transposed it onto wood and cut it out with a jig saw. After that I screwed a piece of sheetmetal to the wood and used my plasma cutter to create the flat piece. Weld and grind
Here's some pics
http://forum.73-87chevytrucks.com/sm...,7175.150.html