2025 Gmc Sierra At4x Hd Specs. The 2025 gmc sierra 2500 hd at4x aev edition adds functional style from american expedition vehicles trove of aftermarket accessories in a production package. Two engines will be offered in the 2025 gmc sierra hd, both of them displacing 6.6 l.

Here’s a list of official specs for the 2025 gmc sierra hd at4x & at4x aev edition. 2025 gmc sierra hd at4x aev;