My pride and joy (auto-hobby wise) is a 65 C10 LWB, 400SB/t5. Starts and runs great, but recently, with demand on elec system, the ammeter pegs to right. Running or not, hit brake, headlights, fan, blinks all send ammeter to peg right. This to me seems like over charging and I don't know why it is doing it. I've had the instrument cluster out to work on temp gauge and recently replaced the starter. What will cause this and what should I check?