Dream Car Turned Howling Mustang: Darren’s Coyote Swapped Mach I

Darren Slone is a Ford guy who is always looking for his next project. So when he sold his nitrous-fed 2003 Mach I in the spring of last year, he was on the prowl for something new to work on. His initial inclination was to search for a second-generation Ford Lightning F-150, that was, until he stumbled across a one-owner Mach I that was just calling his name. Unlike the one he had just sold, this one was completely immaculate, it was just the car he’d always wanted, and it would be a car that go on to be the best project he’s ever owned.

After finding the car for sale online, he set out on an eight-hour journey from Kentucky to Pennsylvania with the hopes that it was everything the seller promised it would be. As soon as he pulled up on the car, he knew the trip was worth it.

The original owner of the Mach I was an older gentleman who had recently fallen ill and needed to sell it to pay for his treatment. He loved the car and always kept it in his garage, and wanted to see it go to someone who would appreciate it as much as he had. That person was definitely Darren, so the paperwork was filled out  and the car had a new owner. The original owner requested one last drive in the car, and handed over the keys with tear-filled eyes after his final ride in it.

This Mach I had previously been featured as a cover car for American Muscle magazine and was also previously ProCharged with a built 4.6-liter engine. Prior to selling it, the original engine was swapped back into the car. This car had tasted fame and admiration for many years, and it was about to get a lot faster, but it would take a little push on the Mustang’s behalf to get there.

On hour seven of the eight-hour journey, the 4.6-liter engine decided to start knocking from a spun bearing after a few high-speed highway pulls. Darren was heartbroken that it was now going to be a chore to get his perfect Mach I back to driving conditions, before he ever got a chance to experience his new ride. To add insult to injury, Darren had to pull over under an overpass to go get help to tow the car back home. By the time he got back in a few hours, the car had been towed away.

The original owner had no idea this was going to happen. Most of the time, you can’t see these things coming, especially when the car had barely been driven prior to the ride back to its new home. Even at that, he still sent Darren $1,000 back for his troubles, which is a pretty incredible thing to do.

After he finally got the Mach I back home safely, Darren dropped the subframe out from the bottom, along with the engine, transmission, and wheels. He did this using only hand tools, jack stands, and an engine hoist to get the car just high enough to roll the engine and drivetrain out.

Once everything was out, he tossed around the idea of just building up the 4.6-liter engine and putting it back in, ready to handle some boost. He then had the idea of instead swapping in a 5.4-liter engine from a Lincoln Navigator, but would end up deciding against adding that much extra weight to the nose. He finally landed on the decision to put a Coyote 5.0-liter engine in his Mach I.

With 39K miles on the clock, he paid only $2,200 for the 5.0L engine off eBay to reach his door. Since it came out of a 2014 F-150, the configuration was slightly different than the ones from the Mustang GT. The F-150 engine utilizes a 10.5:1 compression ratio whereas the Mustang sees an 11:1 squeeze.

For only $150, Darren grabbed some Mustang GT cams to get an extra 30 RWHP, and settled on a stock GT intake manifold that came with the Ford Racing control pack harness kit. He opted to use a K&N air filter to help the stock air box flow better, and also grabbed a set of tubular shorty exhaust manifolds to get the car back on the road within his budget. The exhaust was routed into a BBK off-road X-pipes and Spintech mufflers.

To feed the engine, Darren put together a completely new fuel system tailored to the new setup. This left him with enough funds from his budget to use braided lines for the power steering and coolant lines that run to the reservoir.

One surprising challenge was the battery and air box. “The battery needed to be relocated since the coyote air box sits on the opposite side of the engine bay,” Darren explained. He continued that he “we went with an Odyssey lightweight battery and tray that weighs 14-pounds, and sits nicely behind the passenger head light. I placed the Coyote PCM into the fender behind the battery. This required some cutting which really hurt me to cut into the original body but it turned out nicely. The battery cranks very well even in the cold and really surprised me on how well it does.”

Beyond configuring the hood and shaker assembly, the rest of the swap was fairly straightforward. His Mach I already had a T56 6-speed transmission from a 2003 Terminator, as well as an aluminum driveshaft. The drivetrain feeds into 4.10:1 gears in an Eaton Truetrac differential.

It rolls on a fully built suspension with a Maximum Motorsports adjustable panhard bar, Steeda control arms, Koni adjustable shocks, and SR springs. It also has a 6-point rollcage and Steeda subframe connectors. Up front are a set of 17×9-inch AFS Mach I replica wheels, with the same style in 17×10-1/2-inch at the rear. Nitto NT05 tires wrap around the wheels to help him while driving on the street, and the autocross track as well.

After parting out the 4.6-liter engine and getting the extra money back from the owner, Darren only has about $3,500 into the swap, and loves the results. The car now has over 400-horsepower to the wheels, and handles like a dream. Sometime in the near future, Darren is going to install a roots-style supercharger on the engine; with the blower and a few other modifications, he is looking to get 700-horsepower and high nine-second e.t.s out of the build, while also being able to rule the autocross track!

Tech Sheet:

Owner: Darren Slone


Year: 2003

Body Style: Coupe

Color: Azure Blue


Front Seats: OEM

Rear Seats: Deleted


Block: Stock Coyote

Bore x Stroke: 3.629-inches x 3.649-inches

Displacement: 302ci

Compression Ratio: 10.5:1

Cooling System

Radiator: OEM

Coolant: Motorcraft and Redline additive

Hoses: Custom

Fan: OEM

Thermostat: OEM


Intake Manifold: OEM

Throttle Body: OEM

Mass Air Sensor: OEM

Induction System: OEM

Air Filter: K&N

Fuel System

Fuel Pump: Ford GT

Fuel Lines: -8an feed -6an return stainless braided

Fuel Rails: OEM

Fuel Injectors: OEM

Fuel Pressure Regulator: Aeromotive

Powertrain Control Module: Ford Racing Control Pack

Tuning: Ford Racing


Headers: Mustang GT manifolds

Midpipe: BBK off-road X-pipe

Mufflers: Spintech


Transmission: T56 6-speed

Clutch: Mach 600 stage 3

Driveshaft: Aluminum

Rearend: 8.8”

Differential: Eaton Truetrac

Rear Gear Ratio: 4.10:1

Axles: 31-spline

Shifter: Hurst

Front Suspension

K-Member: OEM

A-Arms: OEM

Struts: Koni

Caster/Camber Plates: Steeda

Springs: SR

Bushings: Polyurethane

Sway Bar: Eibach

Wheels: 17×9″ AFS Mach 1 replicas

Tires: Nitto Nt05 275/40

Brakes: OEM Mach 1/Cobra

Rear Suspension

Shocks: Koni

Springs: SR

Bushings: Polyurethane

Upper Control Arm(s): OEM

Panhard Bar: Maximum Motorsports panhard bar

Lower Control Arms: Steeda

Wheels: 17×10-1/2″ AFS Mach 1 replicas

Tires: Nitto Nt05 315/35

Brakes: OEM Mach 1/Cobra

Chassis Stiffening

Subframe Connectors: Steeda welded

Rollcage: 6-point

About the author

Elizabeth Puckett

Elizabeth is a seasoned writer and hardcore gearhead. She was born with motor oil in her blood and a passion for everything that goes fast.
Read My Articles

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