RCB52003 TRW/ROSS Helper Power Steering Gear Mack 20QC4373M. Heavy duty power Steering gear Box Trw helper RCB52003 with casting #: HFB522999. Fit on truck Mack with dual gear box OE #: 20QC4373M. Power steering gear box, gearbox professionally remanufactured to OEM specs, hydraulically tested. New seals, new bearings, shaft replaced and hight pressure tested. This item requires a $675(CAD) refundable core deposit in addition to the purchase price. UPS cheapest rates will be charged on your credit card to pay return core shipping. This charge will be applied on the core refund. All UPS return paperworks will be includes with the shipment. Just call UPS to get the core picked up ready with papers we provide you.