rigidity. Also, a larger fuel tank was mounted, moved from under the driver's seat to under the rear, between the frame rails. A dealer-installed radio became available in 1973, air conditioning became available via dealership in 1975. Electronic, breakerless distributors replaced breaker-point Delco distributors for the full engine line-up, and a catalytic converter was added to models equipped with the 304 V8. In 1975, for the 1976 model year, the tub and frame were modified from earlier versions. The frame went from a partially open channel/boxed frame with riveted crossmembers, to majoritively boxed with welded crossmembers, and from parallel rails to widening fore to aft to benefit stability. and the body tub became more rounded. The windshield frame and windshield angle were also changed, meaning that tops from 1955 to 1975 will not fit a 1976-1983 CJ-5 and vice versa. The rear axle was also changed in 1976 from a Dana 44 to an AMC-manufactured model 20 that had a larger-diameter ring gear, but used a two-piece axleshaft/hub assembly instead of the one-piece design used in the Dana. For 1977, the frame was modified again to a completely boxed unit. Power disc brakes and the "Golden Eagle" package (which included a tachometer and clock) were new options, as well as air conditioning. In 1979, the standard engine became the I6 that now featured a Carter BBD two-barrel carburetor. From 1980 to 1983, the CJ-5 came standard with a "Hurricane"-branded version of the GM Iron Duke I4 with an SR4 close-ratio, four-speed manual transmission. The AMC straight-6 engine remained available as an option, but the transmission was changed from the Tremec T-150 three-speed to a Tremec T-176 close-ratio four-speed. The Dana 30 front axle was retained, but the locking hubs were changed to a five-bolt retaining pattern versus the older six-bolt. The demise of the AMC CJ5 model has been attributed to a December 1980 60 Minutes segment where the Insurance Institute for Highway Safety (IIHS) staged a demonstration to illustrate that the CJ5 was apt to roll over "in routine road circumstances at relatively low speeds." Years later, it was revealed the testers only managed to achieve eight rollovers out of 435 runs through a corner. The IIHS requested the testers implement "vehicle loading" (hanging weights in the vehicle's corners inside the body, where they were not apparent to the camera) to generate worst-case conditions for stability. Special CJ-5 versions