I would be looking at the voltage regulator. Make sure it is plugged in.
Check the two wires (not the big one that bolts on)to the alternator These are connected to the brushes. When was the last time the alternator brushes were checked.
You can get a volt meter at the auto store that plugs into your cigarette lighter to monitor the voltage
Let me know if this helps, If you are not able to do these things, you can bring it up here and we can put our brains together.
I live near Tatum and Bell road.
Ed