This is a great 4wd trail! I really enjoyed driving this little road in the northwest corner of Arizona. And I would have enjoyed it even more if I'd gone the other direction. I drove it westward = downhill. I find it less stressful to drive challenging boulder sections uphill. I'd rather put the truck in low range and just crawl up and over the rocks. Instead, I was riding the brakes almost constantly to control speed as I descended down over the boulders.
I'd say the difficulty is 4 and 5 on the Mitchell scale. The middle 5 miles is like the "rock garden" of Mengel Pass in Death Valley, or like the hard parts of Shuteye Peak in the southern Sierra mountains. However, 5 miles of hard stuff is more challenging than the short stretches of Mengel Pass or Shuteye Peak.
It grabs your attention and keeps it, for a long time. It was slow going, with typical speeds slower than walking speed. I was so focused on the road, I forgot to get out and take photos.
Here's a map of the road. If you're interested, it's an easy side trip (or loop) out of Mesquite, NV. Warning: Do NOT drive this in a standard street car. You will need high clearance, and possibly 4wd if you go uphill = eastward. The red section is Elbow Canyon (the most difficult of the roads hilited). The orange section is only moderately difficult due to an unending stream of embedded rocks in the road. The purple sections are easy.
I was returning from Utah, and I left I-15 just south of the AZ border. I've driven through the Grand Canyon Parashant National Monument several times, but I wanted to take a new route. The main roads in Parashant NM are graded and I wanted something more challenging and interesting. I was very happy to find both. The road got more difficult as soon as I turned west. Crossing a high plateau at around 7,000 feet elevation, the road had plenty of embedded rocks (the orange section). Enough to keep your speed down.
It's possible to make a loop of Elbow Canyon by starting or ending with the green section. I've driven most of that previously and it was easy.
When I finally got to the bottom warning sign, I could then relax (and pee).