If you are unable to buy from Grainger you can get the motor and the 1/4 to 5/16 shaft bushing from Drillspot.com.
The motor is a Dayton CMC 502A and the bushing is a Dayton 6L100/150/4 They sell to the general public.

http://www.drillspot.com/products/381459/Dayton_CMC_502A_DC_Motor
http://www.drillspot.com/products/37379/Dayton_6L100_150_4_Steel_Reducer_Bushing


Last edited by Jim Meier; 12/26/2007 7:27 PM. Reason: Part Number Correction