Casting Dates for Identification
Whether you are hunting for original Chevrolet cast iron parts at a swap meet, wrecking yard, Ebay or Craig's List, it can be very helpful to understand the GM casting date codes. If you are trying to do a correct "numbers matching" restoration, this is a vital tool for you to use.
From the 1920's through the 1960's GM used a casting date system to identify the date when a part was made. A casting number is a raised number which is cast into the block, cylinder head, transmission case, differential housing and many other cast iron parts. Casting dates are a series of raised letter-number combinations.
In the example, "B 15 2", the first letter is the month (i.e.: A=January, B=February, etc.). The first number or numbers "15" are the day of the month, or February 15th. The last number is the last digit of the year. In this example, the "2" indicates 1932, 1942, 1952, etc. You must be able to identify the part within a 10-year range. You can also compare the part casting number (different than the casting date code) with those used for the suspected model year. Again, these are a raised number that is cast into the part. The part casting number will often be found in the Chevrolet Master Parts Books. Many Master Parts Books are available in print. They are also available digitally on CD and are easily searched electronically. Another helpful publication is the Casting Number Listing for 1929-1942. This booklet will help identify part numbers in the Chevrolet Master Parts Books that are not the same as the casting number on the part. It is a crossover list and very useful for these years.
The date code is a convenient way to quickly identify the year of manufacture. However, caution must be taken as factory replacement parts produced several years later, may have the correct casting part number, but an incorrect date code. Try to identify this example: "K 14 1". This is a little tricky. Remember that production on the new models would begin in September or October of the prior year. This code is November 14, 1931 (or 1941, 1951 etc.), which would be correct for a 1932 (1942, 1952, etc.) early production vehicle.Casting numbers also indicate the part number of the cast iron part. An engine casting number of 835501 was used for both 1929 and 1930 engines. The only way to tell for sure what year the engine was made is to decode the date casting number. The combination of the casting number and the casting date are proof positive that you have that hard to find part that is really right for your old Chevy.