I have a 1979 First Gen and my Altenator is bad, so I got a new one but the plug on the new one only has two connector and my original has a four position plug however only two wires go to the plug anyways.

Can I use this or should I order a different Altenator?

 

Use it.. Just rewire. I have an SA with a 2 Plug Alternator. from some sort of GM vehicle

 

I also have a 79, and had to change my alternator about two years ago because the external regulator was dead. The 79 has a four prong plug for the alternator because of the regulator. The 81-85 rx`s have a two prong plug since they have an internal regulator (not sure about the 80). I cut of the four prong plug, and installed a two prong from the 81-85, and it`s worked fine ever since.