Been a while but I finally got around to putting the torsion spring in the tailgate. Made the tailgate open softer and took a little load off closing it up. For the block that holds the end of the torsion spring I just took a thick chunk of metal and cut it to shape with a portable band saw. Made the half moon hole by cutting the block in half and filing a notch in one side then welding it back together. See it in action here
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I still need to adjust the hinges and strikers but it worked pretty good.