I just received my crankshaft for my lawn tractor the cam shaft for that engine was discontinued . it dosent have a oil pump so the camshaft wasent slotted at one end. the newer version is slotted for a oil pump and will work on non oil pump models the original cam shaft has pressed on spline washers on one end. so will i need to remove these and fit them on the new cam ? they look to be thrust washers. cant find any info on these.