Industrial Injection Dodge H Series Race Main Bearings For 89-18 Cummins - PDM-MS-2328HC1989 2018 Cummins H Series Race Main ( Std . 025) Coated. These H and HX Clevite bearings were developed primarily for use in NASCAR type racing but are suitable for all types of competition engines. H series bearings have a medium level of eccentricity, high crush and rod bearings have a hardened steel back and thin overlay. These bearings also have enlarged chamfers for greater crankshaft fillet clearance and are made without flash plating for