Just installed the 3 OEM OR Edition skid plates last night:
Yes it's 3 additional plates, the Nissan USA website
is incorrect. It says "Skid plates - lower radiator, oil pan, fuel tank (SE Off-road), transfer case (SE Off-road)", but in truth all you get stock is the lower radiator plate, not the oil pan (engine cover) plate.
The cost of these are so cheap it's amazing to me Nissan didn't include them on all models. The only rational thing I can think of is purely to differentiate the OR model for marketing purposes. While it makes sense from a marketing standpoint, from my owner's perspective that kind of fake penny pinching annoys the hell out of me.
From Courtesy Nissan
The engine cover skid plate is part number 50842-ESPFR and lists for $14.72.
The transfer case cover skid plate is part number 50884-TSP00 and lists for $14.02.
And the fuel tank skid plate is part number 50890-EA500 and lists for $105.39.
Don't forget to get 13 skid plate bolts, part number 01121-06561 and are $.60 each.
Installation is beyond easy. I did it on a lift mostly for simplicity and better photography's sake, but you could do it on the ground without even jacking up the truck if you don't mind getting a little dirty. A long extension to get that one 12mm bolt up by the driveshaft on the fuel tank cover was the only bolt that took more than 30 seconds to put on.
There's certainly some room for improvement that I'm sure aftermarket people will pick up on in due course. Covering up the front diff, the transmission oil pan, and another plate for the rear diff. But this is a fine first step and protects the most critical exposed pieces, and you can't beat the price.