69 slant 6

I think most were 225 then. My 69 Dart Custom 2 dr was a 225. The easiest way to tell is to look at the length of the hose between the water pump and head. It is longer in the 225 (but still short). Take photos of others cars with you. The casting# on the driver's side block should tell you. I understand that the 2 bbl didn't come until much later (~76) and maybe only on FMJ cars (Aspen, Volare, ...), but no telling what people have mod'ed in 45 years.