Ammeter suddenly operating at +20amps?

Hi everyone, my 75 Duster (318 60 amp alt) was running fine until this evening I took a drive down to the local resturant with my wife. I got in to drive home and noticed that the ammeter was now operating at +20 amps instead of normal 0. Any ideas where to start looking?

Thanks

Yep, most likely the regulator. Mine did the same.