My '08 book:
Bottom of Page 109, 7.F.11 Open Class, paragraph 1.
Page 119, 7.J.4 Production Vintage, "Same as Production but shall have been produced prior to 1956."
Page 120, 7.J.10, Class VG and VF, "Same as Class G or F, except that class is limited to motercycle engines produced prior to 1956."
I've been known to have to take more than one shot at the book before I found what I was looking for.....
Ed