One thing to be careful when purchasing a Data Book. The Book was updated through the year and into the next. There would be pages from 63 in the 64 Book. There was a listing of the dated pages that would be replaced or retained. Possibly the Binders were salvaged between years as well.
Worthpoint.com is a great reference for GM Items sold in auctions.
A 61 Data Book
62 binder same as my 63 Data Books
64 No longer has a flap and snap
65
66
