74 dart sport won't charge

Hello guys. I have a 74 dart sport that I can't get the alt. to charge. I have put everything new on (alt,volt reg,ballast,coil,ign switch,new engine harness, etc...) and still when you start the car the gauge shows it is not charging. When you pull the battery cable off it dies. I saw on here about doing the amp gauge bypass, which I did, still no. If I run a wire from the alt lug over to the battery and start the car, then pull the cable off but leave the jumper wire the car will stay running, but the alt is still not charging. I don't know much about the charge system so any help will be much appreciated. Thanks, Mike