Aftermarket Drivetrain Parts for the Mack CV/GU. Keep your Mack CV/GU truck running strong with top-quality drivetrain parts. From u-joints and pinion nuts to differential seals and input shafts, this product lineup has everything you need. With trusted brands like TPHD and Rockwell, you can count on durable, reliable performance. Whether it s repairs or upgrades, find the perfect fit for your Mack and get back to work with confidence!