It may seem unnecessary to say that the most important step in any restoration, repair or upgrade is starting with the right equipment. However, your project will come to a screeching stop if you’re staring down at the wrong part. Differentials can come in a variety of shapes and configurations, and if you’re set on changing a differential or simply installing a new diff cover, you need to know what differential is currently installed on your vehicle. Here, we help you identify what type of differential you have to ensure your project stays on track and you get the parts you need. The two most common ways to identify your differential are through axle tags or the shape of your differential cover.
Do you have an Axle Tag Number or Axle Tube Stamp?
Your differential is easily and accurately identified by the bottom line of the tag number or axle tube stamp. If it was always that easy we wouldn’t need to go further, but unfortunately years of abuse from road debris have more than likely wiped that number from existence. It’s also important to note that any previous swapping of gear sets or rear end gears will make this method of identifying the types of differentials of little use to you. For the lucky few who have an intact tag number or tube stamp, here are some steps for sorting through Dana and Ford differentials.
Dana & Ford Differential Identification
The Bill of Material (BOM) number is used to identify Dana differentials. Traditional BOM’s are six digits long and begin with the number 60 or 61 followed by 1 or 2 digits, such as 605561-1. Later-model BOM’s may start off with the first three digits of 200 rather than 60 or 61, for example 200561-1.
Ford differential tags are a bit more direct. The tag number is ordered as year, month and day with the month of manufacture following the format of A for January, B for February, C for March and so on. A Ford tag number will appear something like 12D04 which signifies April 4, 2012.
Identify by Differential Cover Shape
Like we said, if it was as easy as reading a number, this article would’ve ended at the beginning. Unfortunately, the problem is thanks to your love of off-roading and years of dirt and dust, your tag number is long gone. Fear not, you can determine the proper diff for your ride by answering one question: what does your differential look like?
Without an ID tag, differentials are identified by the number of cover bolts, the distinctive shape of the cover, the number of ring gear bolts, and ring gear diameter. They can also be identified by whether the center section is an integral or dropout design. Dropout differentials are also referred to as 3rd members or pumpkins.