The trans valve body parts are included with the automatic transmission components that power an engine's transmission. Although there are a variety of parts that work together, each one is specific to the vehicle and need to be replaced according to factory recommendations. This ensures the part will fit and work.
Over time, the parts of a transmission wear down. Many of the elements of the trans valve body are manufactured to resist corrosion, and they're crafted from durable materials. However, when making a complete transmission repair or working with other components, replacing these minor parts increases the lifespan of the vehicle engine.