1989 Ski-Doo Repair Manual, Page 375Get this manual
Section 04 ELECTRICAL SYSTEM Sub-section 03 (SPARK PLUGS)
SPARK PLUGS
NOTE: The 1989 Bombardier snowmobiles are using two (2) spark plug brands, Bosch and NGK spark plugs
BOSCH SPARK PLUG TYPE
SPARK PLUG NUMBERING SYSTEM