Funny you mention this. Same 2005 Dodge 2500 diesel reg cab 6spd, original batteries replaced a year and a half ago with AGM. Someone told me that the purity of the lead used back then was better than what is recycled so much today. My truck sits alot. It is a garage queen with only 22,400 miles, original Michelin tires with no cracks on the sidewall but you would not want to drive on wet roads too much. Wonder what battery manufacturer uses virgin lead anymore. My old 2014 BMW had the factory battery for years also..