spacers

Does anyone know of a good source for rudder shaft spacers (one [1]- 4 5/8 OD X 3 17/32 ID X 1/4, and two (2)4 5/8 OD X 3 17/32 ID X 1/8) for a 1988 Ericson 35 III? I assume these must to be manufactured out of Nylatron or Delrin? Also, any recommendations on the best method for reducing shaft...