2026 GMC Sierra HD SLE Overview The SLE is the step up from the base Pro trim in the 2026 GMC Sierra Heavy Duty (2500HD/3500HD) lineup. It adds more comfort and technology features while keeping the Sierras serious work-truck capability. GMC 1 Performance & Capability Engine & Transmission: Standard 6.6L V8 gas engine paired with an Allison 10-speed automatic transmission designed for heavy-duty towing and hauling. GMC Strong Towing: Like all Sierra HDs, the SLE can tow and haul with heavy-duty capability (exact figures vary by configuration and whether you opt for the available diesel engine). GMC Off-Road Options: Optional packages like the X31 Off-Road Package (with Rancho shocks and skid plates) are available if you want added ruggedness. Price includes: $1000 - Buick & GMC Consumer Cash Program. Exp. 06/01/2026