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How to Decode a Truck VIN: Weight Class, Engine, and Plant

September 11, 2026

A truck VIN holds something a car VIN rarely makes obvious: the weight class. It is the difference between a light pickup, a heavy-duty work truck, and an 18-wheeler, and you can read it from the number. Once you know where to look, a truck VIN also tells you the engine, the fuel, and where the truck was built.

Everything below comes from NHTSA’s public vehicle database (vPIC), using nine sample VINs decoded from a compact pickup up to a Class 8 tractor.

Start With the Weight Class

NHTSA reports a Gross Vehicle Weight Rating class for trucks. It is the quickest way to place a truck. Here are three groups from our samples:

Notice the jump between the F-150 and the F-250. They share a maker and the same 1FT prefix, but they sit in different classes. The VIN is how a buyer, an insurer, or a fleet manager tells them apart without trusting a badge on the tailgate.

Nine Truck VINs, Decoded

These are sample VINs built for this guide, with placeholder serial numbers. They are not real trucks. Each passes the check digit and returns a clean decode.

Two Things the Samples Teach

The same engine size can hide a different engine. The Ford F-250 and the Ram 2500 both carry a 6.7 L diesel. NHTSA reports the Ford as an 8-cylinder and the Ram as a 6-cylinder. Displacement alone does not identify an engine, so read the cylinder count too.

Heavy trucks decode differently. The three Class 8 trucks are listed as truck-tractors with a 6x4 drive layout, meaning six wheel positions with four driven. They carry engines of about 15 litres, a size no pickup comes near. A pickup shows a drive type like 4WD or 4x2. A tractor shows an axle configuration.

Truck Prefixes Worth Knowing

The first three characters name the maker and, usually, the vehicle type. These are the ones in our samples, as NHTSA lists them:

“Incomplete vehicle” is a real category. It is a chassis sold to a body builder who finishes the truck as a dump body, a flatbed, or a utility bed, so the VIN of the finished vehicle can read differently from a factory pickup. A prefix names the company that registered the code, which is not always where the truck was built. The Ram sample here shows it: its 3C6 code is registered to a Chrysler plant in Toluca, while NHTSA reports that this truck was built in Saltillo. For other makers, see our WMI code reference.

Year, Plant, and Check Digit

All nine samples are model year 2016, which is the letter G in position 10. Position 11 is the plant, and the letter changes with each maker’s factories. The VIN model year codes chart has the full list.

The ninth character is the check digit, worked out from the other sixteen characters, and NHTSA accepted it on every sample. How to calculate a VIN check digit shows the arithmetic.

Check a Truck VIN Yourself

Paste any sample into the VIN Decoder and you get the same model, engine, and plant NHTSA returns. If you manage a fleet, the Bulk VIN Validator can check a whole list of trucks at once and flag typos.

NHTSA’s database is built for vehicles sold in North America. Some heavy or specialty vehicles carry fewer decoded details, so confirm important facts with the maker or the paperwork.

Keep Reading

• How to Read a VIN: What All 17 Characters Mean
• How to Decode a Chevrolet VIN: Country, Plant, and Engine
• How to Tell What Engine a Car Has From the VIN
• How to Decode a Toyota VIN: Plants, Models, and Engines

Free VIN tools: VIN Generator · VIN Decoder · VIN Validator · Bulk Validator · Check Digit Calculator · Bulk Generator · QR Code Generator · Visualizer

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