I was just browsing around for pricing. Anyway I got a couple questions. What's the difference between cat-back style and header-back? How do you know which series your getting? I narrowed the results by jus putting my model and year (1970) and engine size (350). I think that's it. Thanks.

Cat back systems use the OEM exhaust till the outlet end of the catalytic converter. A header back system is a complete exhaust system less the headers. Your 1970 vehicle did not have a catalytic converter.