1983 Chevrolet Truck wiring

I have a 1983 Chevy 3/4 ton with a carbrated 350 automatic 4/4. The tail lights have been acting up and the alternator has quit charging. So now every were I go I must UN hook the battery. It did the same thing to me about two months ago but I thought it had come out of it but happened again starting Saturday march 28. I drove it to work that morning and it all worked fine but when I was gonna go to the store I turned on the lights nothing came on. The dash lights did not come on and no tail lights.