1974 NASCAR International Stock Car Racing Rule Book Limited Sportsman and Hobby Divisions Section 20D-12 -- Clutch and Flywheel

a. High speed clutch assembly permitted.

b. Flywheel may be aluminum. A steel scattershield, not less than 3/8 inch thick, must be installed over flywheel and clutch area. Special construction all-steel clutch housings are permitted in lieu of separate scattershield[sic]. "Clutch-Flywheel Flexible Housing Safety Shield" is approved for use.