Quick Axle ID: 9.75" vs Super 8.8"
Look under your truck. Match the cover shape. You'll know which rear end you have in 30 seconds.
Both rear ends share 12 cover bolts, 34 axle splines, and 31 pinion splines. The cover shape is the only reliable visual ID.
A Tale of Two Rear Ends
As we said earlier, there are two different differential options for the 2015-2025 F150s: the Ford 9.75" and Ford Super 8.8". The Ford 9.75" has been around for a very long time, though it's had some minor changes over the years, and the current variant of the 9.75" was introduced in 2011 and hasn't seen any major changes since (at the time of this writing). The Ford Super 8.8" was introduced in 2015 as a replacement for the older Ford 8.8" that has been around since the times of myth and legend. The change was most likely to consolidate parts and interchange between the F150s and the new Mustang's Super 8.8" IRS. The problem is that both the Super 8.8" and the 9.75" have 12 cover bolts, which makes an easy visual identification a pain. Moreover, both rear ends have 34-spline axles and 31-spline pinions, and the rear ends aren't tied to your truck's VIN, so even a dealer may not be able to tell you with information you provide. The only way to tell is by how each differential and differential cover looks.
The Ford 9.75" Rear End
The 9.75" rear end is the old war horse of the two available rear ends for the 2015-2025 F150s. The good news is that the 9.75" is extremely distinct in how it looks, and in our experience, is the more common of the two differential options. The 9.75" has a very noticeable taper the goes toward the passenger's side of the truck on both the top and bottom of the differential cover. The taper gives the 9.75" a noticeable "nose" that you can easily see when you take a peek under your truck's rear bumper. To accommodate the big 9.75" diameter ring gear, the 9.75" rear end's stock differential cover has a noticeable bulge on the driver's side, which is another dead giveaway that your truck is equipped with a 9.75".
The Ford Super 8.8" Rear End
The Super 8.8" fount on the F150s in solid axle form and the S550 Mustangs in an IRS configuration, is the new kid on the block. Built specifically to replace and update the venerable Ford 8.8" that's been around in various forms since 1983, the Super 8.8" has higher spline counts all around, which likely helps it better handle the increased power and torque of the newer vehicles. In our experience, the Super 8.8" is a little more rare than the 9.75". Only our 2015 2.7L EcoBoost Project and our 2015 F150 5.0L Desert Runner were equipped with one. Compared to the 9.75", the Super 8.8" is not visually very distinct and would be easy to mistake for pretty much any other truck axle. The Super 8.8's differential cover is shaped like a rounded off hexagon without a noticeable taper toward either end. On the passenger's side upper and lower corners, there's two semi-circular divots that can easily be seen when looking at the cover from straight on. While the Super 8.8's cover has a bulge for the ring gear, it's not anywhere near as pronounced as the 9.75's.
Now You Know. Let's Build It.
Once you've identified your rear end, get the right gears for your build. Stage 3's own S3M gear sets are F-150-specific, in stock, and ready to ship. Still not sure which axle you have? Call us directly at 623-434-5277 and we'll help you ID it over the phone.
Shop In-Stock S3M Gears Shop DifferentialsFrequently Asked Questions
How do I tell if my F-150 has a 9.75" or Super 8.8" rear end?
The differential cover shape is the only reliable visual identifier. The 9.75" has a pronounced taper toward the passenger side and a noticeable bulge on the driver side for the larger ring gear. The Super 8.8" is more rounded with a hexagonal shape and two semicircular divots on the passenger-side corners. Both have 12 cover bolts and the same axle and pinion spline counts, so bolt count alone won't tell you.
Are 9.75" and Super 8.8" parts interchangeable?
No. Despite sharing the same bolt count and spline counts, the ring gears, gear sets, lockers, and differential covers are NOT interchangeable between the two rear ends. Always confirm which axle you have before ordering gears, lockers, or covers.
What years and trims have the Super 8.8" in the F-150?
The Super 8.8" was introduced in 2015 to replace the older Ford 8.8". It's found in some 2015-2025 F-150s, typically on lower-output engine configurations like the 2.7L EcoBoost and certain 5.0L V8 trims. The 9.75" is more common across the F-150 lineup. Since the rear axle isn't tied to your VIN, the only reliable way to confirm which one you have is to physically inspect the differential cover.
Is the 9.75" or Super 8.8" stronger?
Both are robust axles for the F-150, but they're built differently. The 9.75" has a larger 9.75-inch diameter ring gear, providing more surface area for power transfer and traditionally being viewed as the heavier-duty option for towing and big tires. The Super 8.8" uses higher spline counts and a more modern design, providing strong torque capability in a more compact package. For most stock and lightly-modified applications, both are sufficient.
Why can't I find my rear end information by VIN?
Ford does not encode the rear axle assembly into the VIN for F-150s. Even Ford dealers may not be able to confirm which rear end your specific truck has without physically inspecting it. Door jamb stickers, axle tags, or QR codes on the axle housing may have the information, but these can be illegible on higher-mileage trucks. Visual identification of the differential cover is the most reliable method.
Can I swap a Super 8.8" for a 9.75" in my F-150?
Technically yes, but it's a major undertaking involving complete axle assembly replacement, driveshaft compatibility checks, and brake-line considerations. For most owners, it's far more practical to upgrade the rear end you have with stronger gears, a locker, or an aftermarket differential rather than swap to a different axle assembly entirely.
