Any 4x4 with larger tires can benefit from a gear swap. That's especially true for a truck that you want to use for off-roading, driving on the highway, and towing. Having the right gear ratio to make the powertrain work the most efficiently is crucial.
The tires we'll finally install on the Ultimate Super Duty next month are monsters. We discovered the Michelin XML line of tires a couple of years ago, and have been dying for a chance to use a set. The extreme trails we want to take this truck on, and the overall look we are trying to achieve, made it the perfect candidate. We'll give you more details on our tires next month, but the ones we chose have an overall diameter of 46.7 inches. When we called Tom Reider at Reider Racing for new Precision Gears for the truck, he was quick to point out that his 5.13 gears we really needed wasn't available yet. While we usually opt for doing the impossible, Reider suggested that we use the 4.56 Precision Gears that are actually available now.
Since this truck will be expected to do everything, we opted for ARB Air Lockers front and rear. Many people don't realize that ARB makes a locker for Ford's Sterling 10 1/2-inch rearend, but ARB does. We used an ARB compressor, which Off Road Unlimited mounted underhood for us.
While we were on the phone with Tony Curtis of ARB, we ordered the company's beefy Sahara Bar front bumper and winch mount. This bumper is designed to provide a safe winch mount and general front-end protection while maintaining airbag compatibility. The shape of the bumper improves the approach angle of the Super Duty. For parking lot obstacles, the Sahara Bar has polyurethane cushions.
For an aggressive sound and a performance gain over stock, we added a Flowmaster exhaust system. The system includes a Delta 70 Series fully welded Flowmaster muffler with 3-inch inlet and outlet. Also included with the system is a single mandrel-bent aluminized tailpipe and all of the hardware you'll need to install the exhaust system.
We drove the truck to Off Road Unlimited in Scottsdale, Arizona, where they installed the Precision Gears and ARB Air Locker in the rear axle. ORU also handled the installation of an ARB bumper, PIAA off-road driving lights, and the Flowmaster exhaust system.
Finally, we dropped the truck off at Rhino Linings to have the bed sprayed with Tuff Stuff polyurethane to protect the sheetmetal and improve the looks. The lining covers the scratches and dings we've already put in our Super Duty's bed. We know we'll appreciate the nonskid surface when we're using the truck to tote parts around.
With literally days left before we left on the Ultimate Adventure, the Ultimate Super Duty was coming into its final form. Next month, we'll wrap things up and give you a look at the final product.
02. Our two biggest concerns when it came to the rear axle was getting a gear ratio to offset the massive tires we'll be running and adding a strong and versatile locker. We're using an ARB Air Locker and we ordered a 4.56 Precision Gear ring-and-pinion set and a complete installation kit from Reider Racing. | 
03. Off Road Unlimited removed the factory differential and ring-and-pinion. A low-mileage truck like ours makes the job a little easier, but we still had to completely disassemble and clean the axle. |
04. Ford Super Duty trucks use a tone ring mounted between the carrier and the ring gear. This ring sends a signal to the ECM for the ABS, speedometer, and auto tranny, and must be transferred to the ARB Air Locker carrier for the ABS to function properly. | 
05. With the pinion-depth set, ORU installed the new differential in the Sterling rear end and checked the mesh pattern on the gears. The copper air line will be routed through the housing next. |
06. For a clean appearance and the ultimate in air-line durability, we used ARB's optional heavy-duty line. The standard kit comes with blue plastic line and push-together connections. While we've rarely had trouble with these, the heavy-duty lines look invincible. The line threads onto the bulkhead fitting on the housing with a 90-degree hose end. | 
07. Ford did not leave much space vacant under the hood. ORU squeezed the ARB air compressor in just behind the airbox. We also used an ARB accessories connection (the quick disconnect is visible in this photo), which allows you to connect an air hose to the compressor to fill tires. |
08. The Flowmaster exhaust system comes with everything you'll need to completely change the sound and performance of your Super Duty. The kit installs quickly and has a single tailpipe. | 
09. The factory bumper comes off by removing the eight bolts surrounding the recovery loops. The original brackets are replaced by the ARB brackets, which also relocate the recovery loops just under the new bumper. Ford trucks come with a Blocker Beam, which keeps most small cars from sliding under the vehicle during impact. We left ours in place as protection for the radiator and transmission-cooling lines. The ARB Sahara Bar attaches to this beam. |
10. The front bumper will be where we mount our Warn M15000 winch, and will provide a nice location for our PIAA 580 Series Extreme White driving lights as well as withstand some abuse off road. | 
11. To help minimize bumping into things behind us, we added a PIAA backup light. We mounted the light to the framerail and then wired it to come on when we put the truck in Reverse. The PIAA kit comes with a toggle switch, which allows you to turn the light on manually or with the factory backup lights. |
12. Our final improvement for this month was to have the bed of the truck sprayed with a Rhino Liner. The polyurethane lining protects the bed, provides a nonslip surface to help hold cargo in place, and improves the look of the bed considerably. You can opt for a variety of colors, but we prefer black. | 
12. Our final improvement for this month was to have the bed of the truck sprayed with a Rhino Liner. The polyurethane lining protects the bed, provides a nonslip surface to help hold cargo in place, and improves the look of the bed considerably. You can opt for a variety of colors, but we prefer black. |