With General Motors itself getting in on the spyshot action on its new 2014 fullsize trucks, there will be little surprise when the Chevrolet Silverado and GMC Sierra are officially unveiled in December. These photos peel back the curtain more than before, giving us the best look yet at the key similarities and differences between the two trucks.

Although it's hard to get too wild with the basic shape and configuration of a pickup, GM is attempting to give the Silverado and Sierra unique looks, at least from the front. The GMC has a more aggressively-shaped hood, with a more prominent "power dome" and an in-your-face three-bar chrome grille. The front fenders also have a creased, angular look, similar to that of the GMC Terrain crossover.

The Chevrolet's look, meanwhile, is slightly more toned-down, with a less prominent hood design and smoother fenders. However, it's clear Chevy isn't ceding much ground to the GMC when it comes to grille size. The lower half of the 2014 Silverado's grille extends further downward than on the current model while retaining the overall bisected theme of the current Silverado. Around back, there is much less differentiation between the two trucks. In fact, only small differences in taillight design differentiate the two models.

The trucks will get at least one variation of GM's fifth-generation small block V-8 at launch, almost assuredly the 5.3 liter with direct injection, with more displacements to follow. Rumors continue to fly regarding the base V-6 and a possible EcoBoost rival, but no substantial technical details have been revealed on either of those engines.