My 75 280's zx alternator died, so i bought a new one, and i had it running for a couple days, but then suddenly it will not run without jumper cables attached. After jumping the car and takling tyhe cables off, i measured the battery and it reads 11.9 volts. This cant be a problem with the...

Would like to start off with saying hello to everyone here as this is my first post. This is pretty confusing problem to me so I'll try to be as specific as possible. Recently picked up a 76' 280z from southern Cali. Drove from Texas to get it, and trailered it back. Immediately the alternator...