were only used in 1969 due to the design being 'frozen' at this specification so production could commence) on Ford's 1967 GT-40 racing block to improve rated power to . According to some reports, the canted-valve, deep-breathing, high-revving engine could produce more than , although as delivered, it was equipped with an electrical revolution limiter that restricted maximum engine speed to 6,150 rpm. A strong bottom end, thicker cylinder walls, steel screw-in freeze plugs, race-prepared crank, special HD connecting rods, and Cleveland-style forged pistons kept the engine together at high speeds. The key to this engine's power was the large-port, large-valve, quench-chambered, free-flowing heads. The Boss 302 Mustang was offered only for the 1969 and 1970 model years. In the January 2010 issue of Hot Rod magazine, a Boss 302 engine built to the exact specifications, settings, and conditions of the original engine was tested. It produced 372 hp at 6,800 rpm and 325 lb-ft of torque at 4,200 rpm. 302 Also, a 302 cu in 335-series engine 302 Cleveland was produced by Ford Australia for the Australian market. By 1967, the Ford GT40 MKII and GT40 MKIV had dominated the Le Mans 24-Hour Race for two consecutive years, using various versions of the Ford big-block engine. In an attempt to reduce the high speeds, the organizers of this race capped the engine capacity in 1968. Ford consequently returned to the MKI GT40 (originally using the Windsor 289), but had now increased its capacity to meet the new rules. Since Ford had ruled that the GT40 engines must have a direct link back to its production cars, the 302 was adopted in domestic manufacturing. In 1968, the small-block Ford was stroked to , giving a total displacement of . The connecting rods were shortened to allow the use of the same pistons as the 289. It replaced the 289 early in the 1968 model year. The most common form of this engine used a two-barrel carburetor, initially with 9.5:1 compression. It had hydraulic lifters and valves of (intake) and (exhaust), and was rated (SAE gross) at at 4,600 rpm and at 2,600 rpm. Optional was a four-barrel version rated at at 4,800 rpm. The 302 was manufactured in Windsor from 1968 to 1978. Ten years of manufacture was punctuated by several design changes, some small or larger. In 1970, the manufacturing of the engine was moved from Windsor, Ontario to