The General Motors heavy duty Chevy Silverado and GMC Sierra 2500 and 3500 are powered by a 6.0-liter gasoline engine that tows 16,700 pounds (with a fifth wheel hitch). Dodge’s heavy-duty Rams 2500/3500 have a 5.7-liter Hemi gasoline V8, 5.9-liter turbo-diesel 6-cylinder or 6.7-liter diesel six. Towing capacity maxes out at 16,600 pounds.