Introduced a few issues back, this 2008 6.4L Power Stroke has already seen an array of bolt-on upgrades intended to not only increase power for pulling, but to do it more efficiently than it did in stock form. Used as a daily driver, this higher-mileage F-250 doesn’t see much more than 35 mph on small town streets during the week, but come Friday afternoon, it’s hitched to a big living-quarters horse trailer or 38-foot RV trailer almost every weekend from April to September. It sees a lot of highway miles traveling the Idaho rodeo circuits, and getting up and down steep mountain grades while keeping EGTs, coolant temps and fuel stops to a minimum is of utmost importance to the owner.

The One Up Offroad Adjustable Coil Leveler (ACL) kit offers complete control of your front end lift height to not only account for front to back level, but also side to side. The threaded spacer allows the coil spring to ride anywhere from stock height to a 2.5-inch increase over stock for fitment of larger tires, for getting the stance back after adding a heavy bumper and winch, or for just bumping an already lifted coil spring truck up a little bit more.

Part One addressed the power and efficiency of the big Power Stroke while maintaining all the factory emissions equipment and keeping it 100% compliant with CARB-certified parts. The Banks Big Hoss Bundle offered a great package for improving horsepower while maintaining cool fluid and exhaust temperatures under heavy load on hot summer days. The high-flow Techni-Cooler intercooler and Ram Air intake ensure cool, fresh air gets into the motor, while the dual-tip Monster exhaust helps usher spent gases out. For tuning and in-cab monitoring, the Banks Six Gun with IQ offers full-color touchscreen technology and gains up to 100 hp over stock, along with control of the turbocharger’s variable vanes via the optional Speed Brake controller for additional braking on downhill grades.

The level kit install is straightforward and can be done in just 1-2 hours with basic hand tools. This truck was raised in a home garage without the use of air tools. To start, you need to get the front coil springs out of the truck. With the frame rails up on jack stands and the axle on a floor jack, the lower shock bolts can be removed.

Part Two covered upgrading the front end with a tough Throttle Down Kustoms steel front bumper. This not only improved the look of the truck with its aggressive styling and near-perfect fitment, but it offers added protection against potential run-ins with wildlife on back country highways in the middle of the night. The optional push bar was the perfect place to mount an additional light bar to help light up those lonely, desolate mountain highways.

Next, disconnect the sway bar end links from the sway bar, disconnect the brake line bracket, and the ABS line from the axle. This will allow you to lower the axle away from the truck; you’ll need to drop it far enough to remove the factory coil springs from their perches.

In this installment, the front and rear differentials will get some love with a much needed fluid service and new high-flow covers from One Up Offroad (OUO). These covers help improve oil flow to the bearings for extra insurance against ring and pinion troubles while towing heavy. The front end of the truck will get some attitude adjustment with the OUO Adjustable Coil Levelers (ACL), which can raise the front suspension up to 2.5 inches over stock for better tire clearance and overall looks.


With 140,000 miles on the odometer and no knowledge of the previous owner’s maintenance schedules, more often than not you’ll find the differentials and transfer case services get neglected, so to be sure everything is fresh it’s always a good idea to flush and fill them with new fluid after buying a used truck. On the 1999+ four-wheel-drive Super Duty Ford, the Dana 60 front axle and Ford 10.5 rear axle offer great strength and functionality, but their basic differential covers’ lack of drain plugs and their silicone seals make servicing a messy and tedious job. Looking to solve some of these issues, the crew at One Up Offroad engineered what they refer to as a high-flow cover that can increase bearing life due some specific internal characteristics cast into the cover for better oiling within the differential gear set.

With the factory coil springs removed from the truck, you can then unbolt the lower spring perch from the axle and discard; the new OUO leveler adjustable mount will replace it.

After consulting directly with Dana Spicer, the manufacturer of the Dana 60 axles used on the 1999-2016 Super Duty trucks, OUO determined that increasing the overall oil volume wasn’t really needed. Spicer’s failure analysis just didn’t back the claims of axles overheating or lacking oil volume. OUO determined that an aftermarket cover that could help the ring gear splash oil onto the pinion bearings more efficiently was the best way to improve longevity of the axles and internals. OUO had also noticed finding an aftermarket front differential cover for these trucks that would clear the factory tie-rod, track bar and track bar bracket was virtually impossible. With this data to work with, the OUO cast-aluminum cover was developed to fit any Ford Super Duty, regardless of its suspension height or the use of high-strength axle trusses.

Assembling the adjustable perch is simple: Thread the lock collar onto the threaded post, slide the spring perch washer onto the post, and then the spring isolator. Don’t forget the Allen head bolt to tighten the lock collar into place once the Leveler is set at your desired height. On this truck, the owner opted for 1.5 inches up from stock.

The OUO front and rear covers use a machined surface with a groove that accepts a thick 3/16” O-ring to make installation cleaner and easier than the factory silicone-style seal. They also incorporate a magnetic drain plug at the lowest point of the cover to ease future fluid services. But one of the most impressive design features of the cover is the massive 1-7/8” fill port cast and machined into it. This large port makes filling the cover much easier, while allowing you to actually see inside the differential to check the fluid level.


While the added weight of the new TDK front bumper didn’t cause the front suspension to sag much, plans for raising the rear of this F-250 truck to F-350 height with taller OUO Traction Bar lift blocks when the OUO Traction Bar kit gets installed (stay tuned for Part Four of the project), something needed to be installed to add some front-end tire clearance. The Adjustable Coil Levelers from OUO seemed the perfect solution, as their unique threaded post design allows complete height adjust-ability by raising or lowering the lower coil spring perch to your desired level. The real beauty behind this style of leveling system is the fact that it will have no effect on ride quality since you’re doing nothing to chance the coil spring compression rate, but can change the front suspension height anywhere up to 2.5 inches over stock.

The supplied line management tab is set onto the axle, then the adjustable leveler system can be installed using the supplied bolt. Be sure to use some Loctite on that center bolt and torque to 140 ft-lb.
With the OUO Level installed, the factory coil spring can be reinstalled, along with all the other pieces you unbolted. Raise the axle back up into place, reattach the ABS lines, brake line brackets, lower shock bolts, and sway bar end links.
Since the used truck was purchased a little high on mileage and had been used for towing, the owner opted to service the front and rear differentials to be sure the fluid was fresh. This meant it was the perfect time to upgrade to the cast aluminum high-flow OUO covers as well. This can help with oil flow to the bearings and future services, since the OUO covers are designed to improve flow to pinon bearings and offer an easy fill port and magnetic drain plug.
The OUO front cover for the Dana 60 under the Ford Super Duty trucks is one of the only high-flow covers available that will clear the factory steering linkage, like tie-rod, track bar, and track bar bracket. They also use a 3/16” O-ring for sealing, and the big 1-7/8” inspection port makes it easy to fill and check fluid level without the need for a dipstick.
OUO didn’t just make a nice-looking, easy-to-service differential cover; the team spoke with Dana Spicer, manufacturer of the Ford Super Duty front axle, to ensure they engineered a cover that would improve oil flow to the bearings. Additional volume wasn’t really needed, just better flow to the pinion bearings to increase service life.

The kit installs in around two hours and you’ll be able to fine-tune the stance and rake of the truck to fit your personal preference. With just a 33-inch tire and stock wheels under the truck and the factory F-250 block still out back, the front end was brought up 1.5 inches for now. But as the rear suspension is upgraded and raised up another two inches, a set of taller 35-inch tires may be considered, so this ACL system may get adjusted to the full 2.5-inch height to improve looks and tire clearance, but that’ll be revisited if and when the time comes. And while it doesn’t pertain to this build, for those already running big aftermarket lifts under their Super Duty with taller coil springs, the OUO Adjustable Levelers could still be added to get you another inch or two, or simply to fine tune your final lift height front to back or even side to side.

The rear differential cover on the 2008-2010 Ford Super Duty is small improvement over previous model years, with its aluminum construction and cooling fins, but the lack of a drain plug and the silicone needed to seal it makes servicing the differential a messy job.
Like the OUO front differential cover, the rear cover for the Ford 10.5 rear axle uses a thick 3/16” O-ring to seal the cover to the axle, making installation much easier and mess free with no more silicone to bead on and wait to dry. You can also see the large fill port plug OUO uses to make fluid changes and checks much easier.
This truck may have a lot of miles for its age, but the rear differential was still in perfect condition with no excessive play, no wear on the gears, and with some fresh gear oil and a new cover it should be good for quite a few more miles.
Since the OUO covers use such a large fill port, they also include a custom machined key that can be inserted to tighten or remove the plug. Also note the magnetic drain plug used at the lowest point of the cover, which makes future fluid changes completely mess-free.
Once the axle surface was cleaned of the old silence, the OUO cover was installed using the supplied hardware; oil can be added until it spills out of the upper fill port. You may notice the cover doesn’t increase volume by much, but again, with this axle, volume isn’t what is important—it’s all about oil fl ow to the bearings. This cover design allows the ring gear to splash oil more efficiently to the vital points within the axle.


While the cosmetic and performance changes to this 6.4L Power Stroke haven’t been very drastic, their ultimate impact is more than noticeable while towing and daily driving. The additional horsepower and torque have helped keep massive loads moving, while the Banks Speed Brake has helped keep that same load under control when coming to a stop. The differential covers should extend pinion bearing life under the harsh towing conditions this truck will see every weekend, and the added height up front just plain looks better on this truck. In Part Four of this project build, the rear suspension will get some minor tweaks with OUO F-350 traction blocks and a set of short gusset traction bars to help prevent axle wrap under heavy load and acceleration. DW



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