Yes, that was the only difference for the front and rear bumpers. The holes are there only for the emblem.

I think his comment was more along the lines that there are many, many cars being passed off as 400 cars that people don't add this detail to them. I have a real 1968 "400" car, as in my PHS documents show that it came from the factory with option 345, which was the 400 engine. It was in an accident and had a replacement front bumper which did not have the emblem. I was able to locate a factory bumper from another member here with the appropriate holes for the emblem and will go back to sporting the emblem when finished. The holes could just be drilled in normal bumper.