How to Locate Identification Numbers on Heavy-Duty Truck Parts

When customers call in to look for a part from the TPI inventory, we will often ask them for part numbers or other identifiers in order to make the search more accurate and efficient.  Other than a VIN number however (which is also included in registration papers), it is not always easy to find where these numbers might be found on the parts.  In this article, we will talk a bit about general locations and the types of numbers to look for.

General Information

In general, finding identifying numbers on a part is not an obvious task.  Each manufacturer will have their own place to put numbers, and this place will sometimes change between models.


As mentioned above, a VIN number can be found on registration or title papers for the truck.  If you don’t have these on hand, you will be able to find the number in one of several places, depending on the make of the truck. For example, a Peterbilt will often have the number under the lock on the side of the driver’s side door, or on a plaque underneath the steering wheel.  Alternatively, some trucks will place the VIN on the frame itself, not always the easiest place to get to.

Above:  VIN found on the door frame of a Peterbilt.

Above:  VIN found next to the steering wheel in a Peterbilt.


In addition to knowing the model of the engine you are looking for, it is always useful to have the serial number and CPL (Control Parts List) or ARR number on hand. Both of these identifiers can be found on a metal plaque called the engine data plate that is on the engine but, again, it is in a different place for each manufacturer and model.  In general, however, it should not be that difficult to find.

Engine data plate on a Cummins.


If you have the VIN number, you will be able to find information on your transmission.  If not, then you can look for a code that is stamped onto the case or a tag that has been riveted to it.  If you can find neither one of these, then you can take a look at certain features which will help determine what kind of transmission you have. For example, what shape is it (square, like Louisiana or Texas, etc.)?  How many bolts are there? All of this information will help the parts dealer in the absence of any other identifying information.

If your transmission has a plate, it will be found on an area such as this one (there was a plate here at one point, but somewhere in its travels it fell off).


Again, different manufacturers will put the identifying numbers in different places. With Rockwell, for example, the numbers can be found on the front of the axle shaft cover and on the edge of it.  Take a look around the part to see if there is either a tag or embossed numbers.

A Rockwell axle cover with numbers on the front…

…and on top.

Locating parts when you really need them is not always the easiest of tasks, but TPI makes it more efficient.  And, the more information you can have when you call in, the faster we will be able to help you find your part.

4 thoughts on “How to Locate Identification Numbers on Heavy-Duty Truck Parts

  • July 18, 2017 at 7:23 am

    It’s interesting to know that when it comes to finding the VIN number on a heavy duty truck, that there are a few places to look. I never knew that you might be able to see it underneath the steering wheel. That is one place that I never thought about looking at, and I might be able to now figure it out.

    • July 18, 2017 at 8:06 am

      Hi Harper,

      Thank you for your comment, and I am glad that the article helped you out, even just a little bit. Finding the different part numbers on truck parts is not easy, but we wanted to provide certain hints, and I’m happy that we were able to help.

      Have a great day!


  • August 18, 2017 at 1:32 pm

    I’ve been browsing online more than three hours today
    and happy to find How to Locate Identification Numbers on Heavy-Duty
    Truck Parts – TPI Blog. First time I have ever found an interesting article like yours.
    It’s really worth any one’s time to read. In my view, if all web owners and bloggers made
    as good as content as you have, the net would be a lot
    more useful.

    • August 21, 2017 at 8:47 am

      Hi Claude,

      Thank you so much for your great response, and we are very happy that you found our information useful: that is what we aim for! Please keep checking back with us as we publish on a regular basis. We also have a monthly newsletter, so if you would like to receive that (September will come out next week) just let me know and I will add you to our list.

      Thank you,



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