351w flywheel

hey guys, I was wondering what is the difference is between the 164 tooth an dthe 157tooth flywheels? I've always heard that ford used big and small flywheels for small blocks but I'm sorda at a loss. what size flywheel should I get and also will is matter on what bellhousing and starter I use. thanks ahead of time.
 
the difference is the diameter of the flywheel mostly. the larger flywheel allows a larger clutch disc to be used for better grip. you do need to size the bellhousing to the flywheel as starter location does change. you cannot use a 164 tooth bellhousing with a 157 tooth flywheel, or vice versa. one way the starter will not engauge the teeth, the other way the start gear jams against the flywheel.