ENGINE Caterpillar engines are identified with SERIAL NUMBERS and AR- IDENTIFICATION RANGEMENT NUMBERS. In some cases MODIFICATION NUMBERS are also used. These numbers are shown on the serial number plate mounted on the engine. The Specification Section at the back of this Parts Book indicates the location of the serial number plate. Caterpillar dealers need all of these numbers to determine which components were include on the engine when it was assembled at the factory. This permits accurate identification of replacement part numbers. ORDERING Quality Caterpillar Replacement parts are available from Caterpillar dealers PARTS throughout  the  world.  Their  parts  stocks  are  up  to  date  and  include  all  parts  normally  required  to protect your investment in Caterpillar engines. When ordering parts, your order should specify the quantity, part number, part  name  and  the  serial  number,  arrangement  number  and  modification  number  of  the  engine  for  which  the  parts  are needed. If in doubt about the part number, please provide your dealer with a complete description of the needed item. HOW TO USE THE Caterpillar Parts Books PARTS BOOK include illustrations of the groups or assemblies which make up the engine. These illustrations show the standard components plus many of the attachments available for the engine. The alphabetical index located in the front part of the book should be used to determine the page number on which specific illustrations are shown. Reference to those pages will identify each of the individual serviceable parts. Captions The caption under each illustration identifies the part number and name of the group or assembly shown.  If more than one illustration is included for any group, the caption identifies the specific engine serial numbers to which each illustration applies. In some cases it is not possible to determine the specific engine serial numbers to which different illustrations are applicable. In those cases the caption identifies the illustration as "First Type", "Second Type", etc. Reference to the actual group or assembly is necessary in those cases to determine which illustration should be used. Captions provide additional information such as page numbers where illustrations of sub assemblies are shown, information reguarding quantities used and other information intended to assist the user in determining parts needs. Indented Within each illustration is a Part Names parts list identifying each serviceable part in the illustration. When a part name is indented in this list, it means that serviceable item is a part of the serviceable item under which it is indented. Abbreviations and Symbols t  Used to call attention to additional * information shown elsewhere within the illustration. R.H. Right Hand Refers to the side of L.H. Left Hand the  engine  as  viewed  from  the flywheel end. C Indicates changes from the previous illustration of the same group, assembly. O.D. Outside Diameter I.D. Inside Diameter N/S Not Serviced Assem.Assembly in. Inch ft Foot cm  Centimetre dm  Decimetre Note: Continuing improvement and advancement of product design may cause changes to your engine which may not be included in this publication. Each publication is reviewed and revised, as required, to update and include these changes in later editions. Whenever a question arises regarding your Caterpillar product, or this publication, please consult your Caterpillar dealer for the latest available information.