3406/3406A (1973): Introduced as a 14.6L engine, offering 310–425 HP.
3406B (1987): Highly popular mechanical engine, 310–485+ HP, known for high torque (up to 1,850 lb-ft) and reliability.
3406C (1993): Further refined mechanical model, capable of up to 625 HP.
3406E (1993–1999): The first fully electronic version, widely considered the best for power and efficiency before being replaced by the Cat C15.
Heavy Duty Pros +