Our 2009 GMC pickup is equipped with a Duramax diesel - and a voltmeter on the dash. So was our '04. And in both trucks the "normal" voltage showed about 14 - 14.3 (as close as I can interpolate the hashlines in the display). I've never put a more calibrated meter on the system to see if it really is running at 14+V, but - our truck doesn't have an ammeter, just a voltmeter.
