1974 NASCAR International Stock Car Racing Rule Book Modified Division Section 20C-10 -- Clutch and Flywheel

a. No dog clutch or similar design allowed.

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