Like I said Rob, you were really close the first time; and NSTG8R nailed it. It's an RC Scale truck hand made.I have seen some extremely detailed models, having followed the model train hobby on and off over the years, though never taking part myself. Those guys are insane with the details!
For starters, the gravel is wrong. It's too big. It's common practice in the model train hobby to use gravel that is too large for scale, because the real scale gravel looks like powder. The stuff that is too big for scale looks better, but it's also the wrong scale. That's what the gravel in your pictures looks like. It's the wrong scale.
Second, the brush guard across the front grille looks too rough. Typical of chromed, injection molded plastic. When you get in so close to get a picture, the imperfections start to show. That's fine for a scale model, but no one who slammed down the wad of cash that truck would have cost if it was real would have settled for what would be a shitty job for a an expensive brush guard.
Third: The antenna looks wrong. Too thick.
Whoever built the model did a very good job. And the photographer did a good job, too. There's nothing I can point to that screams "fake", it just doesn't feel right. But even so, there's no way that's a real, full-size Chevrolet Silverado dually.
Here's the whole story on it:
Chevy 3500 Dually Toy Conversion by Karl Sandvik
About the only thing that gives away the scale of Karl Sandvik’s Chevy 3500 Dually work truck is the size of the hex heads on the custom steel frame rails! We’re suckers for a truck that nearly suckers us! Karl tells us he chopped up a Tamiya CC-01 front suspension for it, widening the suspension arms and substituting dogbones from a different Tamiya model to keep the 4WD functional. The powertrain is based off of an old RC4WD dual-motor transmission that feeds power into the original output shaft for the CC-01 rear axle. The rear axle itself was modified to accommodate RC4WD leaf springs for a scale-correct suspension. He had to fabricate a custom-length driveshaft to work with the long wheelbase. Power comes courtesy of a pair of Novak Terra Claw 55t motors and an Outcry Dual Motor controller. Rolling stock consists of RC4WD 1.9 Double Trouble II wheels wrapped in Dirt Grabber tires. The body began as a Newbright Silverado 1500 which required major plastic surgery using styrene to become a convincing 3500. New bedsides, rear doors, roof, windows, grille, hood, and bed interior (with battery stashed beneath) were required. There’s also a full interior and a set of magnetically attached tow mirrors. He brazed the brush guard, tube steps and rear hitch from aluminum. Front to back the scale authenticity is first-rate!
I'm figuring the size to be around 18" long, about 12" tall and about 11" wide; weight would be around 14lbs from the parts used it's a 1/10+ scale. It doesn't say how it's geared so I have no idea of speed or distance, but if it's typical, it can probably do 35 to 40mph.
I've been into RC gear for about 10 years and own about 30 of them; none of the caliber in the truck pictured; mine are more take them out and enjoy them, not shelf queens.
There's a site I belong to that is all about realistic scale vehicles, the construction and military is probably the most popular.
They have meets all over the world where they set up an area the size of a basketball court like a small city it show how they all work; EU, UK are some of the leaders. This site is about 4X4
http://www.scale4x4rc.org/home/
And this about Trucks and Construction
http://www.rctruckandconstruction.com/index.php
All Scale
http://scalebuildersguild.com/forum/
And just part of my workshop
http://tcurc.com