Restomod muscle cars are nothing new. In fact, we wouldn't be surprised to see in a few years' time even more fully electric restomods given the rapid pace automakers are taking these days to drop combustion entirely. It will happen, sooner rather than later. This doesn't mean combustion-engined vehicles will immediately become illegal, but rather it'll be forbidden to sell new ones. California has already initiated such a plan.

But until then, classic muscle car enthusiasts who want the styling but prefer modern-day guts have a variety of components to select from, such as a Ford 5.0-liter V8. And yes, it can easily fit under the hood of a first-generation Mustang, such as this one up for auction on Bring A Trailer.

This 1966 Ford Mustang was modified recently with the installation of said engine, a five-speed manual transmission, an 8.8-inch limited-slip differential from a 1996 Mustang, upgraded suspension, and four-wheel disc brakes. There's even a custom exhaust with MagnaFlow mufflers, and yet the car still looks completely stock from the outside. But if you look closely there are 5.0 badges indicating it's not exactly stock under the hood.

The seller swapped the original engine for one from a 1991 Mustang GT donor, hence the reason why there's a five-speed manual, not a six-speed. This also means a total of 225 horsepower and 300 lb-ft of torque which, by today's standards, is not exactly thrilling. A turbo-four-powered Focus RS has 125 more ponies.

The engine transplant (true mileage is unknown) also included the replacement of the core items like the vibration dampener, fuel injectors, gaskets, hoses, temperature sensors, and motor mounts. A new fuel pump, fuel lines, and a wiring harness were recently installed. Other notable features include cool 15-inch Magnum 500 wheels with chrome finish, Bluetooth and USB-equipped RetroSound Hermosa radio, and parchment vinyl seats.

The interior is mostly stock; there aren't even power windows. There are a few minor exterior imperfections that can easily be repaired, such as some paint chips, and scratches around the windshield and rear glass. The sale also includes many spare parts and a Mustang-branded car cover. The auction will conclude this Tuesday and the highest bid is currently just $15,250.