Although period images exist showing both straight and angled hood louvers on Types 642 and 644,
all existing images of Type 646 show angled hood louvers.
Presumably the angled-louver hoods were installed on the last cars produced.
Click on a picture to see the full-sized image.
1914 catalog
image source unrecorded
The same car as the image to the left
Courtesy of Alan Woolf