Alternator wiring

I have searched what's the alternator generates and what I have found it is most likely a 60-70A. My car is a Swinger from 73. I also want to just see if it is charging or not, I'm not interested if it's accurate. Want to protect my A-body from fire as well too. As the diode has two legs should I use them both or just one? I found the MBRP400100CT diode on ebay so I'm going to order it soon.