Brazilian Dodge Dart 76 (similar to 69 usa)

Now I'm confused. I allways tought that our 318 engine were identical.
I found in user manual from a 74 brazilian dart "original plug ngk-f6p"
Once I posted a picture from an original plug.. it's clear that we do not have a flat base plug :P



I will try to do a little reasearch about it.. Now I'm confused and curious