I don't make a lot of content with the 2020 GMC Sierra AT4 HD, and it's been a good truck since I've picked it up, but now that the L5P Duramax and 10L1000 10-speed powertrain have crossed 36,000 miles, we're officially out of the bumper to bumper warranty. I figured this was a perfect milestone to document some of the good and bad that the GMC AT4 HD has gone through. Overall, the 2020 GMC Sierra HD AT4 has been amazing, the interior quality is great, I love the blacked out scheme of the AT4, and the L5P is surprisingly fuel efficient for such a big and heavy truck. For the most part, the first year of ownership and the first 35,000 miles went without incident, but the last 1,100 miles has required quite a few trips to the dealer to fix some issues that have popped up. Today we'll cover everything from leaking windows, fuel injectors, the transmission, and everything in between.

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External Shotgun Mic for outside shots
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