Well I have no clue why its called a radio addapter but its this little box that goes on your speedo gear or something and then goes to you speedo cable. The box has some little gears in it that can either slow or speed up the rev's of the speedometer. If you have heard of it and know about it do you think I can use this on a electric speedo or is that just for gear driven speedos?

 

A raTio adapter is what you mean...and that kind will only work on a cable-driven speedo.

Pete