Dodge and GM Dana 60s used cast-iron centersections that placed the pinion gear below the centerline of the differential. For the ’78 F-350, Ford had Dana build its 60 front axles with the pinion gear placed above the centerline of the differential. This made the pinion-to-ring gear mesh stronger, improved driveshaft angles, and increased ground clearance. Dynatrac took this innovation and improved on it with its own ProRock 60 centersection. The ProRock’s heat-treated, nodular-iron housing is said to be 40 percent stronger than Dana’s, and it’s been sculpted to improve ground clearance by 30 percent (arrow).