PART IDENTIFICATION AIDES Other important aides to proper parts identification appear in the General Informa tion section of this book They are A guide TO LOCATE PARTS INFORMATIOAIW Parts Book Format description and listings of the terms used to describe different Truck Models Axles Transmissions Engines etc A description of what each character means ln the Vehicle Identification Number An explanation of where to look in a vehicle to find special information that is necessary for proper parts identification Truck Series Optional Equipment Listings by model number A complete listing of Abbreviations used throulghouti the parts books A Basic RPO Index in RPO Alpha Numeric order and a word description A Basic SEO Index in SEO Alpha Numeric order and a word description NEW PARTS After the initial issue of a parts book parts added to a particular group in the book for the first time will be identified with a bullet following the part number The bullet will appear only in the issue in which they first appear and will be dropped in subsequent reprints RPO SEO PAIITS Effective with the t979 Model Year all RPO Regular Production Option parts will be in cluded in the Parts Book There will no longer bea separate RPO list available A check of the Service Parts Identification Label or Sales Order will confirm RPO usage In the book RPO parts are clearly identified by description SEO Special Equipment Option parts are normally not covered in the text portion of the parts book They are less commonly used and would tend to clutter up the book making it more difficult to identify Standard ard RPO parts lf however parts that are SEO on some vehicles are offered as Standard or RPO on other vehicles then of course they will be covered in the book When SEO parts information is required yot nnust refer to the Truck Broadcast that applies to the specific vehiclle being serviced see explanation of Truck Broadcasts on Page 8 The Broadcast lists major assembly part numbers and the related parts used to make the installation It does not list the details ofthe assembly lt the SEO involves a major assembly such as a Front Axle Rear Axle or Transmission you then refer to the ap plicable COMPONENT PARTS BOOK for the parts details of the assembly PART NUMBER CHANGES lf one part number is replaced by another part number in the book the text will list the replacing number as Replaces Replaced numbers along with cancelled part numbers will also be covered in the current GMC Part Number Replace ment and Supersessions Book USE OF POSTAL RETIUIRN CARDS Included in each parts book is a sheet of four 4 Postal Return Cards for your use to advise the Parts Publications Oepartment of a specific problem or omission in a particular book We appreciate your taking the time to advise us of specific problems or omissions which will help us to improve the quality of the books All cards sent to the Publications Department are evaluated and appropriate action is taken Our policy will be to automatically answer all cards that require an answer and where the sender has indicated he wishes acknowledgement 3