1fine39,
Your ammeter needs no reducer. Does your alternator have its plug on the actual 'back' of the case? Are the terminals marked R and F in little raised letters on the case?
This plug is referred to as the DA plug and it's how your alternator is powered and how it keeps tabs on the state of charge of your system. If your alternator actually has its DA plug located on the back of the case, as opposed to the circumference of the case, it's an old style that uses an external regulator, which is what you probably do not want.
Take a look and let us know which style you have.
Stuart
