With so many different configurations of Cobra Jet engines, there were several different fans that Ford designed. Each one has a specific use, as indicated in the chart. This would serve as a general guideline, with buildsheet information (if available) being the best way to confirm because of change over dates. The engineering numbers are stamped on the fan blades themselves, and they would be date coded as well (except for the C9ZE-E fans). The fans were dipped in black paint originally and would have runs in them as opposed to being sprayed. A fixed-pitch fan was the most common used during these years with the exception being the flex fan used in 1970.