In the first Transformers movie, Optimus Prime is able to transform into a conventional Peterbilt 379 cab. This is different from the cab-over design of his original Generation 1 body. The Peterbilt 379 is a large, heavy-duty truck that is commonly used for hauling cargo. However, its worth noting that in later movies, such as Transformers: Age of Extinction, Optimus Prime transforms into different types of trucks, such as a Western Star 5700 Concept.