The ones I have are both late 1969 printings and they say 1970 on them. These are fine, but of course they don't have any "newer" car interchange info in them. (In other words, will the 69 Camaro radiator interchange with the 1974 Nova.)
I would get something like a 1975 or 1976 issue. That way you could see what interchanges with later model cars.