GM, or chevy suffix codes are a very misunderstood part of engine identification, and just as under utilized. Very little thorough information has been available to the average enthusiast because GM never released the chevy suffix codes to the consumer. GM dealerships were likely the only ones who new what the chevy engine suffix code meant, until recently.
Chevy suffix code decoder books have been assembled through the hard work of one man, whose father instilled the importance of tracking the chevy engine suffix codes at a very young age. These decoders are his life's work.
What are they you ask? Chevy engine suffix codes are a series identification numbers stamped into the Chevy engine block that represent the combined production number of an engine, equipment options and ratings for the engine as well as the option series of car it was built for. The suffix code is made up of the letters trailing the numbers stamped into the block. The number portion of the stamping is the serial number of the engine.
The Chevy engine suffix codes provide some valuable information such as:
- The car model or truck.
- The year or span of years the suffix code was used.
- The cubic inch displacement of the engine.
- The horse power rating the engine was built to.
- Transmission type used with the engine.
- Regular Production Option (RPO) the engine was a part of.
- Intake type such as 2 barrel carb, 4 barrel, aluminum etc.
- Emissions standards the engine might have been built to meet.
And any other descriptions unique to that engine suffix code.
The classic car restoration enthusiast can use these suffix codes in combination with information provided in Chevy engine casting number guides to ensure his restoration is as close to original specs as possible. Between 1962 and 1968, the VIN number of the vehicle matches the number stamped on the engine, followed by the suffix code. Single suffix code letters were used until 1964 and 2 letter suffix codes were used until 1969, three letters are used from 1970 until now. There are some exceptions to the number of letters in chevy engine suffix codes in each range of years.
Even if your classic Chevy is missing the original engine, it is still possible to use the suffix code located on other parts of the car to determine which engine you should look for as a replacement. Between the combinations of the Chevy engine suffix code, engine casting numbers, and engine casting dates, you should be able to locate the correct engine for your classic car restoration, even if you may never locate the engine with the serial number matching engine stamping.
Here's a good example of how I did it. I have a 1964 Impala that did not have the original engine, but I knew it originally had a 283. I managed to find a 283 with the "D" suffix code and a casting date of 1964 on it. The serial number does not match, but I know the engine at least belonged in a 64 impala. I probably couldn't hope for any better than that.
If you are on the hunt for an original engine, the Chevy engine suffix code decoder is a must have. You can use it combined with a cowl tag decoder, Chevy engine casting number decoder, and a model specific factory parts number guide. This is certainly a winning set of reference books for the classic car restorer.