A problem of establishing a theoretical model of a joint from the measured frequency-response function (FRF) data is discussed in this paper. The model of the joint is considered as a coupled dynamic stiffness matrix, which generally includes six degrees of freedom (DoFs). For two types of least-squares solution the terms of use are clarified. The effect of coordinate reduction on the identification results is demonstrated numerically. Also the effect of added noise is studied. Using a substructure synthesis method and the identified joint dynamic properties the assembly response is reconstructed.