Battery Drain

[nizmo559]

Just bought 1979 280zx for 200 bucks. It runs but has one main problem. The battery has to be disconnected when its not running or it will drain. So every time for start up I have to connect it, run to the driver seat and start up. The guy I bought it from suggested it was ignition related. There is a big half off sell at my local junkyard this weekend and I could pick up the parts I need to fix this problem any suggestions guys? Its automatic if that helps any. Any other parts that would be good to swap in while im at it at the yard?