Just recieved Chopper-Impellar Kit (#675806) ordered from AppliancePartsPro. Old impellar is not cooperating with removal in order to install replacement kit. Impelalr is fragmenting into pieces during removal efforts. 
Perhaps this will help it should be close to your unit.
https://secured.whirlpool.com/Service/SrvTechAdm.nsf/2cd44500d572193285256a45004fd9d6/3e7e820d0030640f85256ab000567212/$FILE/4322455.pdf