To date, the Kloke Locomotive Works has delivered two 1860s-era locomotive replicas; the Leviathan 63 seen here and the York 17, which now earns its living at Steam into History in New Freedom, PA. Although the two engines look very much alike to the general public, and have some mechanical commonality, including modern safety features, there are also a fair number of differences. Both locomotives were built using the engineering specifications and castings that were developed by O'Connor Engineering in the late 1970s for the construction of the Jupiter and 119 replicas at the Golden Spike National Historic Site in Promontory Summit, Utah. The Leviathan is a very close copy of the Jupiter. Both are Schenectady designs. York on the other hand, is a copy of the 119, with some cosmetic changes, such as the Yankee-style balloon stack, to make her resemble a wood-burner. Both York and 119 carry the Rogers brand on their steam chests. Both of the Kloke replicas have single-stage air compressors, air brake reservoirs hidden between the rear drivers, and air brakes, as required to operate on FRA Railroads.

The Leviathan was built primarily as a demonstration engine and aside from the air brakes, Mr. Kloke has done just about everything that is practical to keep her as authentic as possible. Her primary couplers are link & pin style, although the rear coupler can be fitted with a Janney knuckle, to facilitate pulling modern rolling stock. Leviathan's forward coupler is just for show and she cannot pull trains in reverse. Leviathan's headlight is a true oil lamp, although she also has super-bright, battery-powered LEDs inside the lamp box for actual operations. She has no generator on board, so headlight use must be limited. Her only cab lights are oil lamps.

The York, on the other hand, was built to be a working locomotive, capable of powering tourist trains under many conditions. York has Janney-type knuckle couplers at both ends, so she can pull a train in reverse and do yard switching. She has both front and rear box headlights, the latter of which is not prototypical. Although they are convincing from a distance, both lamps have two, large incandescent bulbs inside. The headlamps and cab lights are powered by a gasoline-burning generator that is hidden in the tender. York also has a strap-iron pilot, as opposed to the wooden cow-catcher on the Leviathan.