1974 NASCAR International Stock Car Racing Rule Book Modified Division Section 20C-7 -- Cooling System

a. Radiator and cooling system may be altered in any way, providing top of hood fits. No auxiliary cooling tanks or radiators allowed in driver's compartment.

b. When required by track conditions, and on all asphalt tracks, cars must carry catch or overflow tanks of at least one gallon capacity, made of 20 gauge metal and securely mounted as permanent installation, equipped with approved drain cocks. No tin can permitted. Catch or overflow tanks mot permitted in driver's compartment.