I've done a TON of research and actually have a similar thread going in the 04-08 forum. I basically found out that Tasca Auto Parts is about the only place you can get the mirrors guaranteed OEM. All the others (kool vue, CIPA, Racing Guys via EBay) are "almost" identical but are replications. The only other place to ensure they are OEM is to get them from your dealer, and I PROMISE you....you won't want to do that. My dealer wanted twice the money.
I got a pair from Tasca for $346 shipped....only about $40 than the other brands. I placed the order today. Looking forward to getting them on the truck.
Oh and the part number for an 04-08 is 7L3Z-17682-AE and I think 7L3Z-17683-AE. These are really made for '07 to '10 models, but you can still get full functionality with a couple of terminal switches on the plug.
Newport News, VA