Version 4.0: 1.37 ats game version - Hi guys this mod change standart scs peterbilt trucks engine sounds with real sounds. Peterbilt 389: - Real engine sounds added for caterpıllar engines. - Real engine sounds added for paccar mx-13 engınes. - Cummıns ısx engines using scs 389 sounds. Peterbilt 579: - Real engine sounds added for Paccar mx-13 engines - Cummıns ısx engines using scs 579 sounds.