Alternator wiring help

[Bradydz]

My truck had already had an alternator installed on the engine that worked fine, and I tried upgrading to a high-amp output alternator with a different clip for the wiring. I spliced the new clip on, but after two days, I realized my battery was dead, and the alternator was not giving out the necessary voltage I needed to keep my battery charged.
I swapped back to the old alternator, and realized I had lost the clip that connected, so I picked up a new one at a local auto store. Only problem? I cannot remember which wire was which. Does anyone have any idea on which wire would connect to the "r" post on the alternator? I'd greatly appreciate it. The two wires coming from the harness are blue and yellow, or at least that's what colors they look like. I really appreciate the help, and hope to get it running again.