Another alternator upgrade thread

Just out of curiosity when you said your old/current alt couldn't keep up was that at idle or when cruising? Mopars are notorious for not charging at idle. Also, I suggested the ones at RockAuto because they say its a drop in replacement as was the alternator I was going to go with before I got a deal on a PowerMaster 140amp. I don't see why it wouldn't fit though....