The alternator on my 89 Trans ams needs replacing and I have a working used one that the previous owner gave me in a box full of extra parts. He said it was off of a Camaro, but I don't know what year or engine. It looks the same except that the bolt on the back is in a different spot. The plug is also in a different spot but shouldn't cause a problem. Would it be safe to bolt it on using the two front bolts and leave the rear one off?

 

As long as it is the same series alternator you should be fine. Sounds like it is "clocked" in the wrong position though. You can rotate the rear half to match yours by removing the perimeter bolts/screws. Pry it apart just enough to rotate, being sure to keep the stator with the back half, then rotate to match yours. If you pull it apart too far you will have to reseat the brushes. Most auto repair shops should be able to do this for you.