#f 50

So, my truck died on me. I'm not sure what it is. I tested the battery, and it was only reading 6 volts instead of 12 volts. Come to find of my battery had a dead cell. I went to the junk yard to see if I could get one for like 30 bucks, and with my luck they didn't have one. I ended up going to auto zone. I bought a new battery, and put it in my truck. It worked great took it for a test drive to the store. Everything was running great. As soon as I got to my street my truck started doing the same thing. First my radio turned off, then my headlights and everything on my dash got very dim, then my headlights shut completely off and everything on my dash turned off, my steering wheel locked up, and my truck died. When I try turning the key it makes several clicking sounds like the battery is trying to turn over. The lights in my turn on still, and so do my headlights. Also, if my truck is jumped or the battery charges the truck starts for a little, but it does the same things over again in the same order. So, if you have any idea what it is I'd appreciate the input.