 While externally very close to the original cars, in fact they were built on custom chassis powered by Ford drivetrains and had modern four wheel brake systems for safety.The two replicas were very similar to one another, however the first built (and the one used for most filming) had a manual 4-speed transmission while the second had an automatic.Additionally, there was a slight variation in the location of the horn bulb and the pinstripes on the sides of the hood of the second car, so the cars can be differentiated while closely viewing the episodes.