per engineering notes: Description: PART NUMBER 84560768. MUFFLER ASSEMBLY. IS NO LONGER REPLACED BY MUFFLER 84709892. WHEN STOCK IS EXHAUSTED. IT WILL BE REPLACED BY MUFFLER 84864964.
per answerbacks: PART # 84560768 IS REPLACED BY PART # 19420252.
SPAC WILL PURSUE ALL POSSIBLE OPTIONS AND UPDATE YOU
WHEN MORE INFO IS AVAILABLE.
none of these part number changes are listed anywhere in workbench. Stunning!!!