Fred,
The end of the Speedo cable that goes into the gauge is squared off. Be carefull and make sure that you are alligning the squared end of the cable with the square hole of the gauge drive. I had to carefully (Read very carefully file a little at a time and recheck several times) square up the end of my speedo cable with a file to get it to fit properly. The cable should fit into the speedo drive regardless of if you require an adapator.
I updated my web page today.
http://hometown.aol.com/tdockstett/page8.html
To get an idea of how I routed the speedo cable go to the page on "Cutting holes for harness".
I have more to update on the site.
Okiesnake