It seems the customization has only just begun.

As reported by The Car Connection, order guides for the 2021 Silverado and Sierra HDs show additions to the list of available packages.

While buyers of the 2020 Silverado 2500 could outfit their crew cab truck (in LT, LTZ, or High Country guise) with the Z71 Off-Road Package, bringing on board a beefier suspension and Rancho twin-tube shocks, skid plates, hill descent mode, badging, and 17-inch all-terrain rubber, 2021 adds two new flavors, guides show.

Joining the fray are Z71 Sport and Chrome Sport editions that liven up the model's vast exterior with appearance add-ons, including 18- or 20-inch wheels. The packages differ from the existing, more off-road focused Z71. When a model boasts big sales and big margins, why not cater to the healthy handfuls who want to go a different direction. Adding another box for buyers to check is cash in GM's pocket. Not many people are crying over the Impala.

In the Sierra 2500 order guide, GMC has reportedly added two very divergent new flavors for '21: the Denali Black Diamond and the X31 package. The former is exactly what you'd expect - an even loftier strata of the glitzy sub-brand, while the latter apes the Silverado's Z71 off-road package. Meanwhile, lux off-roader AT4 gains a convenience package that bundles together more niceties and safety aids.

GM hasn't confirmed the new additions, but order guides rarely lie.

As it strives to replenish threadbare inventory and restock hungry dealers, GM is putting the pedal down at its truck plants, adding a second shift at Flint Assembly this week.

a version of this article first appeared on TTAC