How to Decode a Chevrolet Truck Big Block Engine
All Chevrolet engines are stamped with an engine ID code or engine assembly code. This ID has a prefix that identifies what plant the engine was made in. The suffix of the ID identifies the year in which it was made and what the original configuration of the vehicle was when the engine was installed on the assembly line. Here's how to decode your Chevy truck big block engine.
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Instructions
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Disassemble components from the engine as necessary until you have a clear view of the area above the timing chain cover mounting surface on the front of the engine block. If the alternator is on the passenger side of the engine, you may have to move it to see this area of the engine block.
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Locate the engine assembly code.
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Note the first character of the engine assembly code. This is the prefix code. The code possibilities are: "F" (Flint, Motor); "H" (Hydramatic); "K" (St. Catherines, Ontario, McKinnon Industries Canada); "M" (GM of Mexico); "S" (Saginaw Service); "T" (Tonawanda); and "V" (Flint, Engine).
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Note the first four numbers after the prefix code. The first two numbers are the month ("01" for January, "02" for February, etc). The next two numbers are the day of the month the engine was made that was originally installed in the vehicle. For example, "0601" would mean the engine was produced on June 1.
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Note the characters after the month and day. These characters make up the suffix code.
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See Resource below for a link ("Chevy Engine Code Information") where you can go to find information about the suffix code on your big block engine. When you click that link, scroll down near the bottom of the page and look for "Big Block Engine Suffix Code Menu." There is a list of five different ranges. Click on the range that your suffix code falls within.
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Tips & Warnings
The suffix code contains information such as the year and type of vehicle that the engine was originally installed in as well as transmission and displacement of the engine. Just one example of a suffix code is "AAS." Looking up the code, we see that this was a truck made in 1973, with 230 cubic inch displacement (CID) and an L-43 AR transmission.
