Multi-body simulation (MBS) codes have been used in the past years for specific analyses of wind turbine subsystems like drive trains, but have also been used for aero-elastic problems. This paper presents a comprehensive high-fidelity aeroelastic MBS methodology to perform integrated loads analysis according to guidelines with a parameterized wind turbine model. The implementation in MBS of flexible bodies in different levels of detail is described, representing linear and non-linear static and dynamic behaviour. Exemplary loads analysis results with models of varying level of detail are presented and differences in load predictions are compared to other modelling approaches. The results yield that for an advanced MBS wind turbine model with nonlinear flexible body representations, lower blade tip deflections and bending moments are observed compared to linear flexible body models. Different drive train torsional models are also investigated. The 2nd and 3rd eigenfrequencies implying the drive train torsion are influenced by applying multi-torsional drive train models.