70 Duster 340, Volt gauge has been funny for a long time. At idle it would bounce around rapidly between 12 & 14 or so. It speed it would even out.

Last summer I did the bulk head bypass a per Mad Wiring & by passed the amp gauge.

Now it is charging 15 volts all the time! If I unhook the regulator it stops charging.

I have replaced the alt, reg, grounded the reg to the batt but no change.

All of the under hood wiring was moved under the dash years ago to clean up the engine side, so it not as easy to get to.

Something is crossed but I can not figure out, help!