Posted by Jason Locke on 4/25/2020 to Before you Buy
When it comes time to grab new rear end gears, an aftermarket differential, or even just a differential cover for your awesome 2015-2020 F150 build, it's generally a good idea to know what rear end your truck is equipped with before making a buying decision. However, our dear Ford Overlords have made this easier said than done, since both the 9.75" and Super 8.8" rear ends have the same bolt count, axle spline count, pinion spline count, gear ratio options, and Ford's part numbers and QR codes may not be legible for anyone with a decent amount of miles on their truck. The good news is that there's a very distinct visual difference between the two that makes it easy to tell at a glance which rear end your F150 is equipped with, so we here at Stage 3 have put together this handy visual reference to help you out.
A Tale of Two Rear EndsAs we said earlier, there are two different differential options for the 2015-2020 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, though 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 EndThe 9.75" rear end is the old war horse of the two available rear ends for the 2015-2020 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 EndThe 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.
Once you know what to look for, it's pretty simple to tell the two rear ends apart. You'll just have to throw on your reading glasses and take a look under your truck to figure out the difference. If you're still having trouble identifying your F150's rear end, give us a call directly at 623-434-5277 and we'll be more than happy to help you out.