Several years ago Firm Feel was selling a reproduction 16:1 worm gear assembly for do it yourself installation. You could also get it already assembled. I bought the worm gear and a rebuild kit from them and put it in an old, but still good stock 24:1 box I had laying around. I used it in my small block Duster and was quite happy with it. It was four turns lock to lock which is still a lot, but certainly better than the six turns of the old 24:1 box, but still a little more than the 3 1/2 of a power box. As for effort, no one has ever mistaken me for a body builder, but I don't think it was all that bad. I was running 225x60x15 tires on 15x7 aluminum wheels if you're interested.