KIT-GASKET 1874968 - Caterpillar

Many Caterpillar engines are used by Original Equipment Manufacturers (OEM's) as diesel power in their products. Some of these engines are standard Caterpillar arrangements. But many must have changes or modifications to fit an OEM installation. When an engine arrangement has modifications, it is then a special arrangement and is given a modification number.
An Engine Bill of Material gives identification of all of the parts Caterpillar has used to assemble a specific engine. If the engine is a standard arrangement, its Parts Book will show the part number, quantity and illustration of the location of all the parts used. But if the engine is not a standard arrangement, the only complete reference for information about replacement parts is its Bill of Material. The Bills of Material for Caterpillar special arrangement engines are available in the Microfilm Engine Bills of Material Library.
To know if an engine is a standard arrangement or a special arrangement, look on the serial number plate. Two designs of the serial number plate are shown below.
A modification number is shown at (1) and (2) in Illustration 1. If a plate has a number here, the engine is a special arrangement and parts reference is in the Microfilm Engine Bill of Material Library. If the space is blank, use the standard Parts Book for a standard arrangement engine.
Illustration 1.A small paper Index book kept with the Bills of Material section of the Microfilm Library tells which fiche shows the Bill of Material for a specific special arrangement engine. Instructions for use are on the front of the Index.
The Bill of Material on a fiche is a microfilm copy of two or more pages of paper. The first frame shows a cover page of information. Important areas of this page are shown below.
At the upper left corner (Illustration 2) are the Bill of Material Number and the Change Number. Together they make the identification of a special arrangement engine as shown in Illustration 1. They form the number found on the serial number plate and in the paper index.
Illustration 2.
Illustration 3.In the upper right corner (Illustration 3) are shown the engine model number and the serial number range from which the special arrangement engine comes.
Illustration 4.In the chart on the lower part of the page (Illustration 4), column (1) shows the part numbers of the arrangements and groups from which the special arrangement was built. Column (2) shows their names. Columns (3) and (4) show the page numbers and parts books where illustrations and parts references for the groups can be found.
The modifications to the arrangements and groups start on the second frame (Illustration 5).
On this page, column (1) again shows the part numbers of the arrangements and the groups from which the special arrangement was built. Column (2) again shows their names. Column (3) shows the part number and column (5) shows the name of parts added to or canceled from standard parts groups. Column (4) shows whether the item was added (the + symbol) or