Caterpillar 3406B SQUARE EXHAUST PORTS Ensure you're Ready for the Road Ahead with optimal engine performance, with the AFA Industries Cylinder Head for Caterpillar. Thanks to its original design with OEM specs, this engine repair kit is the ideal choice to update an engine's cylinder head, and prevent cracking in vulnerable areas. Designed with heavy duty materials and stronger rib reinforcement for extra protection and durability. FleetPride is your First Click in Heavy Duty .