[OG68]

Sometimes the part has different variations according to the model number. And the model number may be abbreviated in the listing. Such as 42 for 65-71 GTOs, 37 for hardtop models or All for all models.
When I'm looking for a particular part under the group number I always go by the model year, then by the particular model in the description.

The illustration guide does not always show an illustration for every year. But you can still use an illustration for a different year just to obtain the Group Number for the part your looking for, which doesn't change from year to year.