General Motors is going all-electric, but not quite yet.

The GMC truck brand has announced that it is making a diesel engine standard on one of its top Sierra 1500 models.

The extreme off-road GMC Sierra 1500 ATX4 is currently only available with a 6.2-liter V8 and will also be offered with the Sierra's Duramax turbocharged 3.0-liter inline-6-cyilinder in 2024.

The diesel engine accounts for 20% of Sierra 1500 sales and has been upgraded to provide 305 hp and 495 lb-ft of torque, compared to the V8's 420 hp/460 lb-ft rating.

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"Since the launch of the refined Duramax for the 2023 model year, around 20% of all Sierra 1500s sold have come with the engine, and we expect its addition to the AT4X trim to take mix even higher," GMC Sierra marketing manager Will Mellon said.

GMC says the diesel's efficiency allows for Sierra 1500 AT4X drivers to take longer trips into the wild.

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The news comes just a week after Chevrolet announced that the Duramax will be an option for the Silverado 1500 ZR2, which is mechanically similar to the Sierra 1500 AT4X.

The two pickups get a host of upgrades that includes two-inch lift and high performance Multimatic DSSV shock absorbers, which use racing technology that improve both their high speed and rock crawling capabilities, making them the most capable off-road trucks GM has ever sold.

Pricing for the 2024 Sierra 1500 AT4X will be announced closer to when it goes on sale this summer, but the V8-powered 2023 model starts at $83,595.

The diesel Sierra 1500 AT4X isn't GMC's only new model coming next year, however.

It is also launching the Sierra 1500 EV Denali Edition, which is a $107,000 all-electric pickup with a 754 hp dual-motor all-wheel-drive system and an estimated driving range of 400 miles between charges.