A genuine T-bucket has the very small and light two seater body of a Model T roadster (with or without the turtle deck or small pickup box), this "bucket"-shaped bodyshell giving the cars their name. A Model T style radiator is usually fitted, and even these can sometimes be barely up to the task of cooling the large engines fitted. There is never any kind of engine cowling on a T-bucket. Windshields, when fitted, are vertical glass like the original Model T.
Model Ts were being hot-rodded and customized from the 1930s on, but the T-bucket specifically was created and given that name by Norm Grabowski in the 1950s. This car was nick named, as it was the custom of the era, the Kookie Kar which was used in several tv shows and movies. Its first appearance was in the tv show 77 Sunset Strip. A character named Kookie played by Edd Byrnes was the owner of the car on the show.
Today, T-buckets are still a very common hot rod style. They generally feature an enormous engine for the size and weight of the car, generally a V8 of some form, along with tough drivetrains to handle the power and large rear tires to apply that power to the road. The front wheels, in a nod to the Model T's drag racing past, are often much smaller than the rear wheels.
Most are built purely for street or display use, and the big engines are more for show than for need — many are more powerful than the vehicles can actually make use of. Although the body shell is a Ford (in appearance, at least), engines of a wide variety of makes can be found on T-buckets. The small-block Chevrolet 350 V8 is a common choice, since it is relatively small, light, easy to obtain and to improve, and performs well. Four cylinder engines are common also, especially if the car is used regularly. Many people also tend to install blowers (superchargers) on their engines, and some people use modern fuel injected engines.