GENERAL IN FORMATION PARTS BOOK FORMAT This Parts Book contains all standard and regular production option RPO parts for 6 Series School Bus Chassis Models and is arranged in the following sequence Description Page Major Group Index s 1 General information 2 20 Parts Book Indexes 2 Parts Identification Aides 3 NEW RPO SEO Parts 4 3 To Locate Parts information 4 Instructions for Ordering Parts 4 IMPORTANT AR As Required Parts 4 Parts Book Format 5 HEAD Serial Number Designation 6 7 THIS Serial Number Identification Plate 8 Truck Broadcast Parts List 8 PAGE Service Parts Identification Label 8 Major Component Part Number Label 9 Metric Fasteners 9 Metric Conversion Table 10 Truck Model Identification 11 Abbreviations 12 15 Basic RPO Index 16 19 Basic SEO Index 20 Charts Text Groups 0 thru 16 Numerical Alphabetical Indexes The MAJOR Group Index on page 1 tells you that in this parts book Major Group 0 covers ENGINE parts Group 2 covers ELECTRICAL parts etc The Group 0 ENGINE section of this book is then numbered as 0 1 0 2 etc Group 2 would be 2 1 2 2 and so on On the first pages of each GROUP section is a SUBGROUP index Also on the first page of each group is printed a black tab that lines up with the group reference in the Major Group Index in the front of the book By slightly bending the book so that the pages fan out you can quickly see these tabs which are intended for quick reference to speed up the location of any particular group The Text portion of some major groups starts with a listing of the major assembly part numbers Whether or not the assembly itself is stocked and offered for service is so indicated in the quantity col umns preceding the part number Even when not stocked for service complete assemblies can normally be purchased if they are still current in production General Motors currently utilizes two different grouping systems for truck parts books The GMT sys tem is used for all Heavy Duty Model Parts Books and the Warehousing and Distribution Division system for Light and Medium Duty Model Books Both systems use different Major Groups and Subgroups but the main difference between the two is how subgroup parts are handled In the GMT system each type of part is assigned a different subgroup number while in the Warehousing and Distribution Division Group system a subgroup may contain several different but specifically related parts This Parts Book utilizes the Warehousing and Distribution Division Group system and an example of a subgroup in this system is the Air Brake Application Valve subgroup 4 640 which includes boot repair kit plunger seal valve and many other related parts Within a subgroup the major assembly part number will be in alphabetical order Subgroup 4 640 actually covers over 10 different but related items To separate these related parts for faster identification you should note that in the Medium Duty Model Parts Books the subgroup number 4 640 is repeated for each of the different but related parts as in the following example of subgroup headings 4 640 BOOT AIR APPLICATION VALVE BODY 4 640 KIT REPAIR AIR APPLICATION VALVE 4 640 PLUNGER AIR APPLICATION VALVE 4 640 SEAL 0 RING AIR APPLICATION VALVE 4 640 VALVE AIR BRAKE APPLICATION PARTS BOOK INDEXES In addition to the Master Group Index that appears on the 1st page of the book and the subgroup indexes that precede each group there are two other indexes provided for your convenience They are ALPHABETICAL INDEX lists each part covered in the book in alphabetical order and lists the applicable I Group Number NUMERICAL INDEX lists each part covered in the book in numerical order and then lists the applicable Group Number