I am having a similar problem it stays charged enough to start the truck but when I turn any acceseries on the volt meter swings a few volts and I have blown 2 signal fuses. I am going to get the alt checked for the 2nd time. no big deal cause I am replacing the alt with a larger one soon but still a pain

1987 Dodge Ram 50
2.6 5 speed
2 inch body lift 31x11.50 Swamper LTBs
4.62 gears lsd rear and welded front with lockouts
Weber carb waiting to be installed