All the 1st gen boxes are interchangable. Use car-parts.com and punch in your Amigo. Their search engine uses an interchange so whatever it lists will work. There are different part numbers for the boxes, but they do seem to interchange fine.

But, are you *sure* all your linkages are tight? Sloppy steering is much more likely to be a blown idler arm on the passenger side frame rail, and then maybe worn ball-joints in the center link. Have someone wiggle the wheel back and forth while you watch the links. A bad idler will be obvious as the arm and center link lifts up and down before the wheels ever start turning. If you watch it closely, you can see the shaft of the idler arm move up and down inducing the slop.

--Dan