A large number of people are employed in various occupations which involve the storage of tools, supplies and material at their place of work. Such storage space may be available in a basement, at the top of the stairs or in a hallway, along with a considerable amount of floor space. In such cases, the toolboxes, shelving or racks are often permanently mounted in a rigid position so that workers at the jobsite are limited in the size, shape or type of container that can be placed on the fixed mounting arrangement. Also, for such permanent mounting, the toolboxes, shelving or racks have to be customized and cannot be moved from one job to another without the need for dismantling and reconstructing the original mounting arrangement. This involves considerable expense and lost time. An arrangement for mounting a toolbox or the like which allows it to be moved to a new location is disclosed in U.S. Pat. No. 4,655,387 issued Apr. 7, 1987 to J. D. Schmitt for "Tool Box Support." The tool box support consists of a horizontal cross piece at the front of the toolbox frame, an upright member having a threaded pin at its upper end and at its lower end a socket to receive the cross piece, and a post extending upwardly and angularly from the rear of the frame. The cross piece includes a vertical slot which receives the post, and the vertical pin slidably engages the slot to slide the cross piece horizontally along the post. When the cross piece is positioned at a desired location on the post, a clamp is tightened about the post to lock the cross piece in place. However, when the toolbox is moved, a similar clamp is needed to be provided to mount the toolbox at the new location, thereby requiring a considerable amount of time and effort to move the toolbox. It is an object of the present invention to provide a mounting arrangement for a toolbox or the like which allows it to be quickly and easily moved from one location to another. It is another object to provide a mounting arrangement which allows the toolbox to be moved to a different location and then repositioned in the same location so that the toolbox is supported at a location above or below a floor surface. It is another object to provide a mounting arrangement which allows the toolbox to be adjusted in any desired horizontal direction while its supporting bracket is rigidly secured. The mounting arrangement of the present invention includes a horizontal plate extending forwardly of the toolbox, a bracket which extends outwardly from the front of the toolbox and includes a rear horizontal section connected to the plate, and a post having a lower end connected to the rear section of the bracket and an upper end received in a receptacle at the front of the toolbox. The bracket allows the toolbox to be moved vertically relative to the plate, to be positioned at a location either above or below the plate and for easy removal from the plate. In addition, the bracket allows the toolbox to be moved horizontally to a desired location relative to the plate, and a clamp secures the toolbox at the desired location. Therefore, in combination with the mounting bracket, the present invention provides a mounting arrangement for a toolbox which allows it to be moved to different locations while remaining securely supported at a single location above or below a floor surface. According to the preferred embodiment, a vertical hole is provided in the plate and a vertical pin extends from the rear section of the bracket and includes a threaded end which screws into the vertical hole to secure the bracket to the plate. Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.