Check the listing for details. USA Standard Gear ZGK2106 Diff Ring & Pinion Kit Rear. Condition: New, Made in China. Listed at 1020.16 USD. 11.5" AAM 3.73 Rear Ring & Pinion, Install Kit, 4.125" OD Pinion Bearing USA Standard Gear Ring Gear & Installation Kits are an easy way to re-gear a differential with one simple part number. The kits package a ring and pinion set with a Master Installation Kit that contains all the bearings, seals, and small parts needed for a proper install. USA Standard Gear employs rigorous in-house quality testing and inspections to ensure its gears pass dimensional, material, and fitment testing. Available in a wide variety of OEM and aftermarket ratios, USA Standard Gear ring and pinion sets are ready to withstand the rigors of everyday commuting, trail running, and all types of spirited driving. This particular kit contains a 3.