I apologize for my previous post. I had originally thought that because that's what my shop told me. Upon further investigation when I had the wheels off to get my new ones on I discovered they put spacers on. The front has like a half inch or less spacer, very small. The rear is using like an inch and a half or 2 to line up with the front. I looked when I first got it installed but clearly missed the rear ones.
Yes they are heater, power adjust and the turn signal in the glass. I don't have a part number I ordered them on ebay. about 400 shipped http://www.ebay.com/itm/2014-2015-CHEVY-SILVERADO-GMC-SIERRA-POWER-HEATED-SIGNAL-TOWING-MIRROR-PAIR-/181673212716?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A2015|Make%3AGMC&hash=item2a4c913b2c&vxp=mtr