2010 Factory Cobra Jet number 39. This is a 5.4L factory 4.0L Whipple supercharger Cobra Jet build at the Flat Rock Assembly plant (only the 2010 and 2012 Model Year Cobra Jets were built at the Ford factory). The Motor was built by Holbrook Racing Engines for Super Stock competition as a 2012 MY 4.0L combination. The benefit of this configuration is it can compete as a 2012MY 4.0L blower car, ...