I think Fab 51 has the right idea;switching to 12 volts,and negative ground(which nobody brought up) will be more workable for a daily driver,not to mention being able to find accessories for your rig,being able to jump-start your wife's barge if it's battery goes dead,switch to HEi if you want to,and replacement parts for 12 volt are a fraction of the cost of 6 volt parts. Don't get me wrong-if it was my truck,I'd leave it 6 volt,and not worry about a stereo,but since you want to add the music box,you might as well do the full monty and just make it all 12 volt,with an internally regulated alternator.
