Help, car keeps dieing

I have a 1970 dart swinger with a 340. I took it out for a ride and started fine all day. Stopped for a bite to eat and notice when I went back out to start it it started slow. So I drove to a friends house about 15mins away and shut it off for about 5mins and went to start it again and it would hardly turn over and drained the battery. So I jump started the car and drove it 5mins down the road and it died. The tac quiet working, ans turn sognal indicators in the car stopped workif .and I noticed the alt gauge never goes to charge is stays just in front of the discharge side. So would that be a bad alternator or voltage regulator?