Finding Your Ford's Rear End Type
The easiest way to identify your Ford rear end is to look at the differential cover — the metal plate bolted to the back of the axle housing. Ford stamped a code into this cover that tells you the exact type. You can see it without removing anything, though you may need to get under the truck or car with a flashlight. The code is usually a letter or letter-number combination, and it matches a chart that Ford kept in service manuals for that year and model.
If the cover is too dirty to read or the stamping is worn, you can identify the rear end by its physical shape and size. Different Ford rear ends look noticeably different — the housing diameter, the cover shape, and the bolt pattern all vary. Once you know what you're looking for, you can narrow it down in minutes. This matters because rear end type affects what parts fit, what gear ratios are available, and whether you can swap it into another vehicle.
Key Takeaways
- The differential cover code is stamped into the metal plate on the back of the axle housing and is the fastest way to identify your rear end.
- Ford used different rear end types across decades and model lines — 8.8-inch, 9-inch, and Dana 60 are common, but many others exist.
- If you cannot read the cover code, you can identify the rear end by measuring the housing diameter and comparing the bolt pattern to known types.
- Knowing your rear end type is necessary before buying replacement parts, gears, or planning any suspension or drivetrain work.
Reading the Differential Cover Code
Start by getting under the rear of your Ford and locating the differential cover — it's the large metal plate bolted to the back of the axle housing. Use a flashlight and wipe away dirt if needed. You're looking for a stamped code, usually one to three characters, that Ford pressed into the metal during manufacturing.
The code itself is not a full description; it's a reference number. You need to cross-reference it with a Ford service manual or parts catalog for your specific year and model. Different years used different codes for the same rear end type, so the year matters. Online Ford forums and rear end identification databases (maintained by enthusiast communities) have compiled these codes, and many will let you search by year, make, and model to find what your code means.
Write down the code exactly as it appears, including any numbers or letters after it. Take a photo of the cover with the code visible. This information is what you'll need when ordering parts or asking a mechanic what you have.
Measuring and Comparing Housing Diameter
If the cover code is illegible or missing, you can identify the rear end by measuring the diameter of the axle housing itself. Different Ford rear ends have different housing sizes, and this measurement narrows down the possibilities quickly.
Measure across the widest part of the round or oval housing, from the outside edge on one side to the outside edge on the other. Common Ford rear end sizes are 7.5 inches, 8 inches, 8.8 inches, and 9 inches — these measurements refer to the ring gear diameter inside, but the housing diameter correlates to these sizes. A 7.5-inch rear end has a noticeably smaller housing than an 8.8-inch, for example. Once you have the measurement, compare it to photos and specifications for Ford rear ends from your vehicle's year and model line.
Keep in mind that some Ford trucks and SUVs came with Dana rear ends (made by Dana Incorporated, not Ford) instead of Ford-branded units. Dana 60 and Dana 70 rear ends are larger and heavier than most Ford units and are common in older heavy-duty trucks. The housing shape and bolt pattern look different enough that you can usually tell a Dana from a Ford at a glance.
Checking the Bolt Pattern and Cover Shape
The differential cover itself has a distinctive shape and bolt pattern that varies by rear end type. Count the bolts holding the cover on — Ford rear ends typically have 10, 12, or 14 bolts, depending on the type. The bolt pattern (the arrangement of holes) is specific to each rear end design.
Look at the shape of the cover too. Some are flat, some are slightly domed, and some have ribs or reinforcement ridges. The 9-inch Ford rear end, for example, has a distinctive flat cover with a specific bolt count. The 8.8-inch has a different shape and bolt pattern. These visual differences, combined with the housing diameter measurement, usually narrow it down to one or two possibilities.
If you're still uncertain, take clear photos of the cover and housing from multiple angles and post them on a Ford enthusiast forum. People who work on these vehicles daily can often identify the rear end from photos alone.
Common Ford Rear End Types and Where They Were Used
Ford has used several rear end types across its truck, SUV, and car lines over the decades. The 7.5-inch was common in older light-duty trucks and some cars through the 1990s. The 8-inch appeared in some mid-size trucks and performance cars. The 8.8-inch became Ford's standard for many trucks and SUVs starting in the 1980s and is still used today — it's strong, affordable, and parts are widely available.
The 9-inch is a heavy-duty unit that Ford used in commercial trucks, some high-performance vehicles, and certain SUVs. It's larger and stronger than the 8.8-inch and is popular for custom builds and off-road work. The Dana 60 and Dana 70 appear in older heavy-duty Ford trucks and some specialty vehicles. Ford also used independent rear suspensions (IRS) on some cars and SUVs, which look completely different because there is no central differential housing.
Your vehicle's year, model, and original purpose (light-duty truck, heavy-duty truck, passenger car, performance vehicle) all influence which rear end it has. A 1990 F-150 will have a different rear end than a 1990 Mustang, even though they're the same year.
Why Rear End Type Matters for Parts and Repairs
Knowing your rear end type is essential before you buy replacement parts. Gear sets, bearings, seals, and covers are all specific to the rear end type. Ordering the wrong part wastes money and time. If you're replacing gears or doing any internal work, the technician needs to know the exact type to get the right components.
Rear end type also affects what gear ratios are available. A 3.55 ratio in an 8.8-inch rear end is different from a 3.55 ratio in a 9-inch, and they're not interchangeable. If you're planning to change your gears for towing, off-road work, or performance, you need to know what you have before shopping.
If you're considering swapping a rear end into a different vehicle, the type determines whether it will fit, what modifications are needed, and what driveshaft changes are required. Enthusiasts often swap 8.8-inch or 9-inch rear ends into older Fords or other vehicles, but the swap is only possible if you know what you're starting with and what you're putting in.
Frequently Asked Questions
Where exactly is the differential cover code stamped?
The code is stamped into the metal of the differential cover itself, usually on the flat surface or near the edge. It's not painted on — it's pressed into the metal during manufacturing. You may need to clean the cover with a wire brush to see it clearly, especially on older vehicles.
Can I identify my rear end from the VIN?
The VIN contains some information about your vehicle's original equipment, but it doesn't always specify the rear end type clearly enough to order parts. The differential cover code is more reliable. If you have the original window sticker or build sheet from when the vehicle was new, that document lists the rear end type, but most owners don't have it.
What's the difference between a limited-slip and an open differential?
Both types can be in the same rear end housing — the difference is inside. An open differential sends power to whichever wheel has the least resistance, which can cause one wheel to spin if you lose traction. A limited-slip differential uses clutches or gears to send more power to the wheel with traction. You can't tell which one you have just by looking at the cover, but the cover code or a test drive (turning sharply and listening) can reveal it.
Do I need to know my rear end type for an oil change?
You need to know the capacity — how much fluid it holds — which varies by type. The owner's manual lists this, but if you don't have it, the rear end type tells you. Different types also use different fluid specifications in some cases, though most modern Ford rear ends use the same gear oil.
What if my Ford has an independent rear suspension?
Independent rear suspensions (IRS) don't have a traditional differential housing with a cover. Instead, each wheel has its own differential or drive unit. These are common on newer Mustangs, some SUVs, and performance vehicles. If you can't find a differential cover, your vehicle likely has IRS, and you should consult the owner's manual or a Ford dealer for information about that specific system.