70 Dart Stopped Charging

Car was operating fine, but now does not charge battery.

3 wires coming off alternator. 2 Have voltage when car is running. 3rd has voltage when lights are on. "Using crackedbacks wiring mod if that makes a difference"

2. Voltage regulator on firewall test ok.

3. Small silver block with multiple spade connectors next to battery doesn't have voltage where a couple wires are hooked up . I don't know what this is or what it does.

I know this is vague and I will update with better information if you have questions. I can take a few pics when I get home if needed.