That is interesting. I noticed the BBM has the tapered design where the Hemi is the box style. I think both styles were made for the BBC. I do find the tapered street intended design (Vintage design) more pleasing on the eyes than the Box design. I do not care for the looks of the modern versions such as Holley, but I understand this modern design is to flow lots of air and make SERIOUS power with today's available heads.