Eaton 127719 is an oil seal for the differential pinion. A shaft seal like this keeps gear oil inside the housing and keeps dirt and water out where the rotating shaft passes through, and the spring behind its sealing lip helps hold contact as the lip wears. Our parts manual lists it in the Dana Spicer DS/RS 340-402 Tandem Drive Axle (forward axle single reduction, item 61), the DT/RT 340-402 Two-Speed Tandem Axle (forward axle double reduction, item 94) and the DT/RT 440, 460, 480 Tandem Drive Axle (forward-rear, item 3). A genuine Eaton part from Pro Gear and Transmission. Call us to confirm proper fit.Interchanges:119429475012NGMC 15665322Mack 2719-127719Navistar 596310C91FeaturesOil seal for the differential pinionListed in the DS/RS 340-402 Tandem Drive Axle, forward axle single reduction, item 61Listed in the DT/RT 340-402 Two-Speed Tandem Axle, forward axle double reduction, item 94Listed in the DT/RT 440, 460, 480 Tandem Drive Axle, forward-rear, item 3Sealing lip holds gear oil in and keeps contaminants outUsed in these Dana Spicer modelsDS/RS 340-402 Tandem Drive AxleDT/RT 340-402 Two-Speed Tandem AxleDT/RT 440, 460, 480 Tandem Drive Axle