I was kind of thinking the same thing. I have a Chilton's manual for 62 to 72 cars and the only place I could find the FB engine designator was on the 69 Corvette engine specs. I am a beginner at restorations and engine rebuilding. I have worked on my own cars all my life but this is my first restoration car. I am building a 66 Chevy II Nova. Thanks for your help.