A-AR101266-AI Bearing, Main (Std)One New Aftermarket Replacement Main Bearing (Standard) Fits John Deere Tractors, Combines, and Construction Equipment This standard size crankshaft main bearing is a direct aftermarket replacement Fits John Deere equipment powered by the 6. 531 (6 531) six cylinder diesel engine. The main bearing supports the crankshaft within the engine block and is a critical component during engine rebuilds and overhaul projects. This is a standard (STD) size