The first edition of the HQ Parts Catalogue released in 1971 had a very useful section detailing the specifications of every bolt, nut, screw, washer, clip and pin with their accompanying part number, used in HQ Holdens.
This info is extremely useful when trying to find or buy that correct nut, bolt, screw to replace those missing for your restoration.
The listing was dropped from the subsequent HQ Parts catalogues so if you have one of the later parts catalogues, you can’t determine the actual nut or bolt specs. Presume Holden didn’t want you to go to the local bolt shop and buy a bolt that only cost 1/10th of what Holden Parts were selling it for.
The best way to make use of the charts is to find the part number of the nut, bolt, etc from the various assembly diagrams in the parts book, then search the nut & bolt listing for that part number to give you the exact nut / bolt / screw spec.
You can download a PDF of the chart from the following link. There are high resolution images further below of each page if required.