For 1958, GMC reduced the bore of Pontiac's 370-cubic-inch (6.1 L) to 3.875 in (98.4 mm), resulting in a displacement of 336-cubic-inch (5.5 L).

Beginning in 1999, GMC began offering GM's LS-based "small-block" V8 engine in various models.

[3] Beginning in 2001, GMC offered the same turbocharged diesel Duramax V8 engines as were available in similar Chevrolet trucks.

The engine family was co-developed by GM Powertrain and Isuzu, and has gone through numerous iterations through the years.

Duramax engines are paired with a heavy-duty automatic transmission from GM's Allison division.