Alternator drawing power from the battery ground

Hello, I was hoping to find some insight for this issue I am having, if not I know a simple one wire alternator will fix the problem (I think). when I was 17 I messed up by installing an alternator with the battery hooked up and allowed the ground wire to make contact with a positive post on the alternator this caused my wiring harness from the alternator all the way to the voltage regulator to go up in smoke instantly. since then I replaced the entire wiring harness. I think it may charge but the alternator draws power from the batter when car is off. I believe their is a short somewhere but I cannot find it. I find it odd that when I connect the negative battery terminal it causes an arc thus telling me power is being absorbed from the ground. also the alternator will get hot because it is drawing power. this is a 65 mustang with the 1st gen ford charging system set up. I have a new alternator for it but it is not 1 wire I am wondering if the short may be internal in the alternator. thanks for your time I hope I can find some insight that may make it unnecessary to go buy a 1 wire alternator.