Will there soon be a Sierra HD AT4X? GMC appears to be ready to release a rugged version of the highly anticipated Sierra off-roader and we have photos of a prototype testing out these new improvements.

Our spy photographer reports:

Judging by this latest prototype, it looks like the 2023 GMC Sierra HD update will bring a more serious off-road version, signaling a possible expansion of ZR2/AT4X spec capability into GM’s heavy-duty truck space. .

Rumors are circulating of a program within GM actively testing a host of upgrades to go beyond GMC’s Sierra AT4 HD and create a new AT4X HD variant. Engineers reportedly tested several shock options, swapping between upgraded versions of traditional Rancho shocks and heavy-duty versions of the Dynamic Suspension Spool Valve (DSSV) shock technology currently found on lightweight versions of the Chevy Silverado ZR2 and its GMC Sierra. Brother AT4X. Now, with the appearance of this new prototype, it seems that this program has moved from simple internal evaluation to the point of testing on public roads – a significant step in GM’s testing protocols.

This new test truck displays a number of attributes that are consistent with GM’s high-end off-road variants of GM’s midsize and full-size pickups, and represents a likely step above GMC’s current Sierra AT4 HD trucks. moving into AT4X HD territory. Among the visible improvements we see:

Stripped front bumper for better clearance
On the current GMC Sierra AT4 HD, the front skid plate is almost invisible, as it is obscured by the truck’s rather low and thick front bumper. A look at this new prototype’s highly visible (and reinforced) front skid plate tells us that this new bumper design has been kept to a minimum, removing unnecessary, overhanging elements like chin spoilers or air vents. wind. Much better ground clearance and an improved approach angle are in place for more serious off-road riding.

New tires compatible with other ZR2/AT4X trucks in GM’s current (and future) lineup
While the current AT4 HD is equipped with Goodyear Wrangler TrailRunner A/T or Goodyear Wrangler Duratrac tires, this new prototype is equipped with Goodyear Wrangler Territory MT tires. Territory MTs are found on the recently released Silverado ZR2, and have also been seen several times on the next-generation Chevy Colorado ZR2 and GMC Canyon AT4X prototypes. It looks like GM engineers tried to erase the Territory MT lettering on the tires, but the designation is still slightly readable when zoomed in. The distinctive Territory MT sidewall tread blocks are also unmistakably present on this prototype’s tires, confirming exactly what rubber is fitted to this HD test truck.

Disguised wheels, as seen on GM’s other specialty off-road truck prototypes
This off-road-focused Sierra HD prototype has camouflaged wheels, just like we’ve seen on some of the later, more extreme Silverado1500 ZR2-based and Sierra 1500 AT4X-based prototypes (which also get Territory MT tires). The camouflaged wheels on this prototype, however, show an appropriate eight-legged design for this HD application.

A look at shocks
The shocks on this prototype are hard to identify with certainty, but they look different than the red-tube Rancho shocks on the current GMC Sierra AT4 HD. On this prototype, the shocks can display the wider format compatible with the Multimatic DSSV shocks that are currently part of GM’s ZR2/AT4X formula. DSSV shocks are generally not considered strong enough to handle traditional HD-level loads, but rumors have suggested reports that DSSV shocks have actually been tested on GM’s updated HD prototypes. The AT4X HD may be willing to give up some traditional HD capability in exchange for more off-road prowess. There have also been rumors that Multimatic will be developing a new generation of HD-spec upgraded DSSV shocks, which will presumably require fewer compromises between baja-busting and traditional HD-level attributes.

Whether or not this latest GMC Sierra HD prototype is equipped with DSSV shocks, it seems clear that GM is working on a new AT4X HD variant with a more dedicated off-road mission. Now that a prototype has been discovered on public roads, we’ll be on the lookout for similarly equipped test trucks, to dig into its suspension details and to see if something like this is in the works for the road as well. Chevrolet brand.