Auto Parts: 67 dodge pickup fuel guage, gas gauge, dodge pickup

Question
I've got a burned out fuel guage on my 67 pickup.  I have a used replacement but I didn't mark the 3 wires when I took the old one out. The terminals on the guage are marked I, S,and A.  One of the wires comes from the heat guage which is pegged to hot as soon as the ignition is turned on.  Can you tell me what wires go to what terminal.  Thanks

Answer
    Geez, even I'm not that old.  Well, not quite.  Back in the pre-printed circuit dash days, gauges had more than one connection on the back.  I'm pretty sure that the "I" termninal is for ignition, and is probably hooked to that hot wire that also goes to the temperature gauge.  "S" probably goes to the wire from the sender in the tank.  I'm not sure where the "A" terminal goes.  Is the gauge grounded by being attached to the metal dash?  If it is, then I'm not sure what that third wire is for (if it's not, it could be the ground).  The meaning of letter codes on OEM stuff doesn't always make sense to the layman. or me.  I'd try hooking it up without the third wire.  If it works, then I'd hook the third wire to the remaining terminal.  But, I can't be sure of any of this.  I'm pretty sure that it's very hard to hurt a gas gauge and wonder if the old one was really bad and not the sender.  Of course, being over forty years old, anything could have happened.  Marking the wires before you took it off would have been a great idea.