For Sale is a brand new pair of McCulloch sprocket as shown in photo.  It is for the mini 3/8" pitch chain, has 6 teeth.  The bearing is pressed in.  

This fits:
McCulloch Mini Mac 6, 25, 30 and 35

McCulloch Mini Mac 110, 120, 130, 165, 2.0

McCulloch Power Mac 310, 320, 330, 365, 375,  510