Hi all,
Figured I would chime in on this since I live in Cortez, Co about 1.5 miles east of Hwy 666/491.
Hwy 666 was change to 491 in NM, CO? & Ut because the Governor? of NM wanted it changed because 666 was the Number of the Beast & was called by many the Devils Highway. He also got the Federal Gov in on making the change because it is a North south Hwy 7 they are mostly odd numbered Hwys. Even Numbered Hwy are east west Hwys.
I drive from Cortez down to Gallup & up to Monticello all the time to do jobs.
666/491 is good road all the way with a few rough spots.
Mileage going 666/491 from Gallup - Cortez - Monticello - Moab is about 250 miles.
The other route mentioned Gallup - Shiprock - Hwy 64 to 191 - Monticello - Moab is about 280 miles.
Plus there is Major rod work being done ON 191 between Blanding & Monticello. Expect delayS, very narrow sections & sections of dirt road.
So I Recommend taking 666/495 all the way.
Fuel will be cheapest in Gallup most likely.
Mike