dave-r wrote:I thought the square back was 1970 on? Then again. I can't remember which one I even have.
Yes, the square-backs are 1970 and up. The other changeover that I know of was for the ignition in 1972. Some car lines may have got the new alternators later than 1970, but I doubt that.
MLMFLCN, if you wan to check, that's easy. If you have 3 leads going to the alt (the output and 2 field wires), you need a square back. If there's just one field lead, it's a round back (those have the second field terminal bent and connected to the alternator body, so there's no second field wire).
For a stock car, even with a radio, stock amperage is more than enough.
If you add a fuel pump, fans, water pump and headlamp conversion, something like the Powermaster 17509 or one of its brethren will be more like it.
As always, I recommend the amp gauge bypass : running a single heavy gauge wire from the alternator output to the starter relay (something like the 30709 Painless wiring kit).