#13: SPARK PLUGS for Gravely 5-hp Engine - 
AUTOLITE #3076 SPARK PLUG: This is the current part number for the original TT-10 - it is physically and functionally identical to it. Standard heat rating. 
CHAMPION #W-14 SPARK PLUG: Standard heat rating.
CHAMPION #W89D SPARK PLUG: Hotter than W-14.
>>> BE SURE AND CHECK THE GAP BEFORE INSTALLING ANY NEW PLUG <<<