Forget about MSRP, that's a factitious number anyway. What you need is the true Invoice number, which you can get from NADA or Kelley Blue Book and other web sites. You also need the Dealer Holdback data. Then it's a matter of negotiating profit, Dealers like Dave Smith in Kellogg, Idaho often times will give you a price hundreds below Invoice. With other Dealers you can get it for Invoice and still others for two hundred above Invoice or so. I wouldn't pay any dealer more then Invoice.
You still get all the incentives. Dealers will give you the best incentives from the time you order to the time you take delivery of your new truck. Good luck.