Black box under dash

[Mullinsracing]

I just bought a 1984 skier (fixerupper). My question is there is a black box under the center of the dash that has cooling fins on it with 3 electrical posts on it. One post goes to batter +, one goes to alternator, and the other post has nothing on it. I haven't put a multimeter on it to see what it is doing but was hoping that someone on here knows what I'm talking about.

Thanks

[Pistol Pete]

Pic.?

[Mullinsracing]

http://i79.photobucket.com/albums/j126/mullinsracing/9c0bdc3b.jpg

The pic is a little dark but you can see it under the horn

[eyepeeler]

Flux capacitor. Carefull, it emits 1.21 Gigiwatts.

[jk13]

It's an old dual battery isolator.

If you had another battery onboard, it would go to the other terminal. Go ahead and connect the wire from the alternator directly to the battery and get rid of it and the jumper wire.

Until then, don't go 88mph.

[Mullinsracing]

Lol...thanks

[Mullinsracing]

Lol...thanks

[Pistol Pete]

A pic. is worth 1K words.