Parts Programs When your job gets tough, you need to stay on top of your game. That’s why Mack offers parts programs so you can easily stay on top of your truck. These programs support the legendary dependability of your Mack® to keep your vehicle running at peak performance all day, every drive. Purebred Overhaul Mack’s standout Purebred Overhaul program is put in place to maximize the uptime of your engine. With Purebred Overhaul’s extended warranty, revitalizing your engine offers you the increased reliability to ride the road with confidence.