My originals are worn out, I was researching this last week. Here's what I found. Altman are bolt in, but you will still have to cut sheet metal. $350.
Others, like
http://www.hotrodlatches.com/default.asp or Autoloc are a simple bear claw. You will have to do the engineering, cutting, and welding to make it work. $50.
I was telling my Dad about this dilemma. Saturday, he shows up with a set of autoloc bear claws that he isn't going to use. I guess that is the direction I'm going.