These heads used the "dry-deck" technique, meaning no head gaskets were used. Each cylinder, oil passage and water passage had a private O-ring to seal it tightly. The Boss 429 engine used a Holley four-barrel mechanical unit rated at 735 CFM mounted on a associate degree Al manifold that flowed well for the era. The 1969 cars were fitted with a hydraulic lift shaft while the 1970 models received a mechanical lift shaft in conjunction with an improved dual system, although the horsepower rating remained equivalent. The Mustang's body was not wide enough to accommodate the massive Boss 429 engine and as a result, Ford used Kar kraft paper in urban Michigan to replace the stripped-down Jet Mustang four-speeds so They correctly fit the new Boss 429 engine. The kraft paper was contracted by Ford to form the Boss 429, as Ford was stretching over a variety of models, such as the Boss 302 and its Trans Am version which competed in the series of SCCA Trans Am races during the same years. THE