A 1967 Mustang Fastback Lost Its Entire Engine Bay — Builders Moved the V8 Behind the Driver Instead

A 1967 Ford Mustang Fastback — one of just 71,042 built that year — is getting a full mid-engine conversion and a custom widebody kit to match. Here’s how builders are reshaping a factory icon to hide a drivetrain Ford never engineered it to carry.

For nearly sixty years, the silhouette of a Mustang fastback has told you exactly where the V8 lives: up front, behind that long hood, ahead of the driver. A build crew at B is for Build decided that rule didn’t apply to their 1967 Mustang Fastback. They pulled the drivetrain out of the nose entirely, relocated it behind the cockpit, and started fabricating a custom widebody kit wide enough to hide the surgery underneath. From some angles the car barely reads as a Mustang anymore — and that’s the whole point of the project. What’s taking shape under the fiberglass is a car built to a completely different blueprint than Ford ever drew in Dearborn.

The Day the Mustang’s Engine Bay Went Empty

In this episode, the B is for Build team picks up mid-project on their mid-engine 1967 Mustang Fastback, continuing work on the custom body kit that has to stretch and reshape the car’s factory panels to clear the relocated drivetrain. The video is a hands-on fabrication session — templating panel sections, test-fitting composite pieces against the widened bodywork, and making the kind of small, deliberate adjustments that separate a show car from a project that just looks good in thumbnails. It’s the unglamorous middle of a build: the part where a wild idea either gets proven out panel by panel or quietly falls apart.

What comes across watching the process is how much the mid-engine layout changes every downstream decision. A stock 1967 Fastback’s rear glass, deck, and quarter panels were never engineered around anything but a trunk and a live axle sitting well behind the passenger compartment. Moving the engine back into that same space means every one of those surfaces has to be reconsidered, which is why so much of the footage is dedicated to custom composite work rather than just bolting on parts. The crew treats the Mustang’s iconic fastback roofline as a shape worth preserving even as nearly everything beneath it changes, which is a much more demanding approach than simply building a kit car from a blank sheet.

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B is for Build has built its following around exactly this kind of long-form, show-the-process content — fewer polished reveal moments, more hours of templating, test-fitting, and re-cutting panels until they actually line up. That approach matters for a project like this one, where the final body kit has to do double duty: it needs to clear mechanical components that a factory Fastback panel was never designed around, and it still needs to read as a cohesive shape rather than a collection of flared patches. Viewers following the series get to see the compromises in real time — the moments where a panel that looked right on paper has to be trimmed back, reshaped, or scrapped and started over once it’s actually sitting on the car.

Why 1967 Was the Mustang’s First Real Muscle Car Year

The donor car for this build isn’t a random Fastback — 1967 is arguably the year the Mustang first became a true muscle car rather than just a stylish pony car. Ford widened the body and reshaped the engine bay that year specifically to clear a big-block V8 for the first time, giving buyers the option of the FE-series 390 cubic-inch engine under the hood of a car that had launched in 1964½ with nothing bigger than a small-block. The S-code 390 is widely cited at around 320 horsepower, paired with a four-barrel carburetor and the kind of low-end torque the original six-cylinder and small-block Mustangs never had.

That 390 could be ordered with the GT package, which brought power front disc brakes, dual exhaust with chrome quad outlets, and grille-mounted fog lamps — and when paired with a three-speed automatic instead of the four-speed manual, the car became the GT/A. Ford also widened and reshaped the whole car for 1967, adding more interior room and a more aggressive face with a bigger grille opening, while Shelby was simultaneously turning the related GT350 and GT500 into genuine track-bred performance cars built around that same larger body. In other words, 1967 is the year Ford first let the Mustang grow up into real muscle car territory, which makes it a fitting donor for a build this ambitious: it was already the year Ford bent the rules of what a Mustang’s engine bay was supposed to hold.

Only 71,042 Fastbacks Left the Factory That Year

Ford built 472,121 Mustangs across all body styles for the 1967 model year, and the hardtop coupe dominated the lineup with 356,271 units — more than 75 percent of total sales. The convertible added another 44,808 cars. The Fastback, by comparison, found just 71,042 buyers, or roughly 15 percent of the model year’s production. It was always the enthusiast’s pick rather than the volume seller, the body style aimed at buyers who wanted the GT package, the big-block option, and the sportier roofline rather than a comfortable daily cruiser.

That relative scarcity matters here. A mid-engine conversion this invasive is, by definition, a one-of-one modification — there will never be a second car exactly like it — but starting from a body style that was already the rarer of the three 1967 configurations adds another layer to the story. Every cut panel and relocated mount on this particular car is being made to a Fastback that was already less common than the hardtop it’s often confused with at a glance.

A Widebody Kit Built to Hide a Radical Swap

The most visually dramatic part of the project is the widebody kit itself. Relocating a V8 from the nose to the middle of the chassis doesn’t just change where the weight sits — it changes the proportions of the whole car, and a factory-width 1967 Fastback body simply doesn’t have the room to hide a mid-mounted drivetrain along with its cooling, intake, and exhaust routing. The custom composite panels being fabricated in this video exist to solve that problem: widen the car enough that the conversion disappears into the silhouette rather than looking like an obvious hack job bolted onto a classic shape.

Mid-engine layouts also flip the weight distribution a muscle car was originally engineered around. A factory 390 Fastback carries most of its weight over the front wheels, which is part of why big-block Mustangs of this era are remembered for straight-line power more than cornering balance. Moving that same mass behind the driver and ahead of the rear axle pulls weight toward the center of the chassis, which is the same principle that makes exotic mid-engine cars feel so different to drive — and also why pulling it off in a 1967 unibody, rather than a purpose-built tube chassis, is so much harder than it sounds.

It’s a build philosophy that treats the Mustang’s exterior as something closer to a sculpture that happens to be a car. Every added inch of width has to still look like it belongs on a 1967 Fastback, which is a much harder design problem than building a one-off kit car from scratch. Get it wrong and the car reads as a costume. Get it right, and it reads as a Mustang that simply evolved differently than the roughly 71,000 built on Ford’s assembly line that year.

What Makes This Build Worth Watching

Mid-engine muscle car conversions are rare enough that most enthusiasts will never see one in person, let alone watch it built from bare metal and composite layup. What makes this one notable isn’t just the novelty of the layout — it’s the decision to keep the car recognizably a 1967 Mustang Fastback rather than starting over with a purpose-built chassis. That choice means every fabrication decision is a trade-off between engineering freedom and preserving the shape that makes a Fastback instantly identifiable at a car show from fifty yards away.

It’s also a reminder of how far builder culture has pushed past the traditional resto-mod playbook of dropping a modern engine into a classic shell. A full mid-engine relocation, done with a custom-fabricated widebody kit rather than an off-the-shelf conversion package, puts this project in a different category entirely — closer to a low-volume supercar build than a weekend garage job. Projects like this one tend to pull in viewers who have never considered themselves muscle car fans at all, simply because the engineering problem is interesting on its own terms, independent of nostalgia for the original car.

There’s also something worth noting in how the build treats the 1967 Fastback as raw material rather than a finished artifact to be preserved. Plenty of resto-mod culture is built around respecting a car’s original lines while quietly swapping in modern mechanicals underneath. This project inverts that logic almost completely: the original drivetrain layout is gone, the body width is no longer stock, and the only thing truly carried over from Ford’s original design is the roofline and the general proportions that make it unmistakably a Fastback. Whether that counts as restoration, modification, or something closer to a tribute built from donor parts is the kind of debate this build is likely to keep generating as it nears completion.