Does your M4050 have an external regulator?Sounds like you got a different alternator than the one that was on it.
Where did you get it from?
And post pictures if you can.
May be cheaper to try an armature shop. I'm getting new alternators for $15 more then what it costs to have one rebuilt.Me personally just take the old alternator and get the same replacement, then you're done!
And that GM alternator is better than the old stock external regulated alternator anyways.