Hi, i have a 1970 Cadillac Coupe Deville with a 472... i just bought it roughly 3 weeks ago, and my batteries kept dying so i replaced the altenator twiceand and neither of them have been working... i feel as though its a wiring problem but i cant trace it

 

You may have bad voltage regulator. Regulator is separate from alternator and should be mounted on radiator core support. I suggest go to shop that specializes auto electric and have it checked out. If you have modern high watt stereo system; stock charging system is inadaquate and needs to upgraded to be modern high output type.