1974 NASCAR International Stock Car Racing Rule Book Modified Division Section 20C-22 -- Crash Bars

a. Any type crash bars will be allowed and all corners or edges must be rounded. Rear crash bars may be only 6 inches higher or 6 inches lower than frame level. Rear crash bumper may not extend beyond the middle of each rear wheel. Front bumper width cannot extend beyond the inside of front tire. Any inappropriate crash bar will be disallowed, and no snowplow type bumper will be allowed.

b. All cars must be equipped with approved nerfing[sic] bars and scrub rails constructed of steel seamless tubing with a maximum outside diameter of 1 1/2 inches. Nerfing[sic] bars and scrub rails must be fastened to the frame. Nerfing[sic] bars and scrub rails may extend outward to edge of tires, front and rear, and must be not higher or lower than center line of front and rear axles.