A new cast iron lubricating oil pump, Part Number 5532492 , was released to replace an existing aluminum lubricating oil pump, Part Number 3687527, and cast iron lubricating oil pump Part Number 3687528, for some 15L engines. New Part Number 5532492 has different flow characteristics that do not affect lubricating oil system function, but can result in different oil pressure values than expected. Part Number 5532492 does not use shims to set gear lash like existing lubricating oil pump Part Numbers 3687528 and 3687527.