Need a replacement catalytic converter for your 1978 Peugeot 504? MagnaFlow offers high-quality catalytic converters engineered for 1978 Peugeot 504 sub-models and engine sizes. We combine efficient design and state-of-the-art manufacturing to meet or exceed required emissions standards. Select your 1978 Peugeot 504 requirements and state vehicle registration to buy the best 504 catalytic converter online that fits your '78 504 and meets your state’s emissions compliance.