1999 Ski-Doo Factory Shop Manual Volume One, Page 253Get this manual
Section 06 ELECTRICAL Subsection 03 (SPARK PLUGS)
SPARK PLUGS
NGK SPARK PLUG
All Models
NGK SPARK PLUG NUMBERING SYSTEM
Bombardier is using the NGK spark plug type on all its snowmobile modelsThe heat range identification system is: Low number hot plug High number cold plug