QSB4.5 Cummins Main Bearing 3978820 Parts Catalog Ref No. Part Name Part No. Required 　 Engine Crankshaft 5300529 1 1 Spline Coupling Sleeve 4937957 1 2 Shaft Collar 2831066 1 3 Crankshaft Gear 4934419 1 4 Engine Crankshaft 5272079 1 5 Pin Dowel 3904483 1 6 Main Bearing 3978818 4 7 Main Bearing 3978820 5 8 Thrust Bearing 3978822 1 …