Silverado 2500 HD Rear Pinion Flange Dorman 697-572

This is Dorman 697-572, a cast iron rear differential pinion flange that replaces GM part number 12471501. It is the heavy style flange with the round damper weight machined into it, the same as the factory part, so the driveshaft balance and vibration damping come back to where they were. The shipping weight is about 16 lb, which tells you this is not the plain flange used on light-duty trucks.

Listed fitment: 2001-2006 Chevrolet Silverado 2500 HD and 3500, 2001-2004 Silverado 2500, 2007 Silverado 2500 HD Classic and 3500 Classic, and the matching GMC Sierra 2500, 2500 HD, 3500 and Classic trucks for the same years. Check the number on your old flange or your VIN in the parts catalog before ordering, because GM used more than one rear flange on these trucks depending on axle and driveline.

Why it gets replaced: a grooved or rusted seal surface on the flange eats pinion seals, so the new seal starts leaking gear oil again within a few months. Worn splines let the flange move on the pinion, which shows up as a clunk when you shift into drive or reverse. A cracked or out-of-round damper section causes a vibration that climbs with road speed. The Dorman package shown includes a pinion seal, pinion nut and washer.

On the bench: mark the driveshaft to the flange so it goes back in phase, drop the shaft, and check pinion bearing preload before you take the nut off. Pull the old flange with a puller, never a hammer. Install the new seal, lube the seal surface and splines, draw the flange on with the nut, and bring preload back to spec. On a crush sleeve axle, do not overtighten past spec and then back off. That crushes the sleeve too far and it has to be replaced.