Buick La Crosse Alternator Replace/Remove

I Changed Alternator. Battery Is Good And Was Tested. My Gauge Reads All Over The Place, 13.1, 14.7,15.3, Etc. I Turn Lights On And It Will...

The Alternator On My 2005 Buick Lacrosse Needs To Be Replaced. I Have Managed To Get A New One And Removed The Old One. I Am Having...