Absinth is correct in his comment that the drawings have a history box that details the changes made to a part number. however there are probably drawings for the 2817164 which are not in the remaining GMH drawing folders. They were probably removed or lost many years ago as we have been using the folders for some time.We are talking about the drawings for 92003716BA which we do have and that don't have any comment about a thickness change. They are 3mm from start to finish. These are what was used to make the wheels from.