Pigtail issue?

I took the alternator to NAPA in Thayne yesterday. The list price for that model in their computer was under what we paid. We paid $510 for alternator and core, we got $436 back. Maybe if I had waited and taken it back to Eden, NY where it was installed, we might have gotten a full refund, but that would have forced us to return home by a route we don't usually take and don't particularly like (we usually avoid the NY Thruway around Buffalo but last week coming out we were trying to make time because we had been delayed in our departure time) and so I decided it was worth the $75 to have the freedom to go home the way we want to. Also, there was no guarantee it would have been any different. So that's that. The manager at the NAPA store did give me a good tip. He asked if they had replaced the pigtail when they replaced the alternator. I said I didn't know, and I didn't even know what a pigtail was. Turns out that that is the term for the plug that connects the alternator to the electrical system. He said that if the pigtail is defective, that can cause the system to malfunction and burn out the alternator. Maybe that is what happened! I plan to have a mechanic check the pigtail Monday. Meanwhile, the "check engine" light has come on again. That's what happened the morning we left, and we had it checked at Subaru in Brattleboro, and they said it was the catalytic converter. Then, of course, it was a few hours later that the alternator failed. So we are understandably nervous.

This is a pigtail