The development of new and improvement of existing railway rolling stock wagons is an urgent task of our time, providing for cost reduction, both in the process of creation and operation, and in the maintenance of the wagon fleet. The purpose of the work is to modernize the body of a dynamometer wagon for special technical purposes using modeling. To determine the loading of the structural elements of a dynamometer wagon, a calculated three-dimensional model of the wagon body was developed, the reinforcement points of the wagon frame were determined. Compression/tensile strength tests of the wagon were performed on a stand for loading the frames of wagons and elements of coupling devices. The stress-strain state of the wagon structure is determined when statically applied longitudinal test loads are applied to it. The test results and the stress-strain state of the design of the prototype wagon, under the action of statically applied longitudinal compressive and tensile test loads, showed that the proposed design of the wagon meets the established strength requirements, while no visible damage and residual deformations were found in the design of the prototype wagon. The developed design of the dynamometer wagon body can be included in both freight and passenger trains, which solves the problem of efficient and safe use of locomotives when operating trains on mountainous sections of railways of the Republic of Uzbekistan.