Image Credit: Mopars5150 / YouTube.Whereas some muscle cars survive because they spend decades hidden away, others survive because one person simply refuses to let them go, and this silver 1968 Plymouth GTX falls firmly into the latter category.Its owner, Brian, bought the car back in 1975, when the Plymouth was only seven years old. Half a century later, it remains in his possession, carrying a restoration completed in the mid-1980s along with an extraordinary amount of original hardware and documentation.This isn't an ordinary GTX, either. Under the hood sits a 426 Hemi paired with a four-speed manual, making it one of the most desirable configurations Plymouth offered during the peak of the muscle-car era.AdvertisementAdvertisementThe team from the Mopars5150 YouTube channel recently got a close look at the car while visiting Brian and his wife Heather in Ontario, Canada. What followed was a deep dive into a GTX with a history every bit as interesting as its specification.Brian Bought The GTX As A Shell In 1975Image Credit: Mopars5150 / YouTube.Brian purchased the GTX in 1975, although by then its original Hemi was already gone. The first owner had reportedly disconnected the speedometer at around 11,000 miles before continuing to drive the car, eventually developing an engine knock during a high-speed run.According to Brian, the culprit was a cracked piston skirt, after which the original Hemi was removed. A 383-cubic-inch V8 was eventually installed, although that engine was also gone by the time Brian acquired what was essentially a shell.The GTX's body had already endured some adventures of its own. Brian recalled a story involving previous occupants returning from a day of boating when an outboard motor ended up damaging the driver's-side quarter panel, resulting in repairs and a later dark-gray repaint with a splatter-style vinyl roof.AdvertisementAdvertisementFactory documentation indicates the car originally wore AA1 silver paint without a vinyl top. Brian ultimately restored it in 1984, bringing the exterior much closer to its original appearance while installing the proper Hemi hardware again.A 426 Hemi And Four-Speed Make This GTX Seriously RareImage Credit: Mopars5150 / YouTube.The GTX was Plymouth's upscale performance offering, combining muscle-car hardware with a little extra refinement compared with the stripped-down Road Runner. Ordering one with the 426 Hemi, however, transformed it into something considerably more serious.Brian's documentation indicates roughly 450 Hemi-powered GTXs were built for 1968, including convertibles, with 234 equipped with four-speed manual transmissions. The car also carries a Dana 60 rear axle and retains the sort of wonderfully uncompromising specification enthusiasts now chase: manual steering and manual brakes.Its Hemi breathes through dual four-barrel carburetors, while period modifications remain part of the car's character. Headers, a scatter shield, an electric fuel pump, and other details reflect how high-performance Mopars were actually treated decades ago rather than presenting the car as though it had been sealed in plastic from day one.AdvertisementAdvertisementBrian says he hasn't needed to adjust the carburetors since the engine went together. His routine is simple: switch on the electric fuel pump, start the car, and when parking it again, shut off the pump and let the carburetors run dry.Much Of The Interior Is Still OriginalPerhaps the most remarkable part of the GTX is how much old material survives inside. The seats remain largely original, including the rear seat with its factory metal emblem, while the console and shifter are also original pieces.Brian deliberately chose not to replace some worn materials because preserving the authentic pieces matters more to him than making everything appear freshly manufactured. The cracked original dashboard pad and deteriorated carpeting were replaced, although much of what surrounds them is still genuine 1968 equipment.The car even retains period paperwork from the dealership, including documentation showing its original configuration and options. Among them were the Hemi, four-speed transmission, Sure Grip differential, radio, rear speaker, console and optional headrests.Nearly 40-Year-Old Paint Still Looks Remarkably GoodImage Credit: Mopars5150 / YouTube.The restoration paint itself dates to roughly 1984 or 1985, meaning the finish is now around four decades old. There are imperfections, including some bubbling and areas that have received touch-ups, yet the GTX remains remarkably presentable considering how long ago the work was completed.AdvertisementAdvertisementThe underbody also retains substantial original material, including the trunk floor and much of the original sheet metal. Even the wheels currently fitted are old genuine pieces rather than modern reproductions, while Brian still has steel wheels that could bring the appearance closer to its original configuration.Perhaps the best detail is simply the length of the relationship. Brian bought this GTX when Richard Nixon had only recently left office, restored it before many modern classics had even been built, and still owns it 50 years later.Plenty of valuable Hemi Mopars have passed through auctions and collections several times over. This one has spent most of its life with the same caretaker, and that history may be even harder to replace than the 426 Hemi sitting between its fenders.If you want more stories like this, follow Guessing Headlights on Yahoo so you don't miss what's coming next.