O4B is an early big block Edelbrock intake. I've been told the O4B stands for "Olds 4 Barrel". They were made back in the 1970's, not sure just when they started and stopped production. I've been told they are one of the few aftermarket intakes that will fit with a 1970-72 ram air hood/air cleaner but they don't flow nearly as well as the newer intakes such as the performer. They do look nicer than the factory cast iron and reduce the weight as the cast iron one weighs a lot! Not meaning to hi-jack the thread, just trying to answer shak's question.
John