B/RB BIG BLOCKS AND HEMIS
The first letter is the year code, followed by the engine's displacement. Hemi engines have an "H" after the year letter and before the displacement (as in this example), while truck blocks have a "T" in this location. Engine displacements before 1965 may have a digit missing: 36=361, 38=383, 41=413.
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This line contains the build date and what number engine that was built that day.
• The first number is the month (or a 4-digit 10,000 day calender date).
• The second number is the day of the month (or a 4-digit 10,000 day calender date).
• The third number is the build sequence for that day. This example engine was the 6th built.
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The last line carries any secondary information pertaining to the build of the engine. Any symbol or letter on this line had a special meaning. This example engine has an A (oversize cylinder bores), P (premium fuel only) and a small diamond (oversize tappets).
The following is a list of letter codes and their corresponding years. The year always precedes the engine displacement.
