For sale is an arbor (spindle) nut with washer for the 103.22161 or 103.21040 Sears Craftsman 8" bench table saw.  The nut is 1/2-20 R.H.  The washer is 1-3/8" O.D. They may fit other models as well.  

The arbor (spindle) is seen in photos, is not included.