Linear viscoelastic G’ and G” mastercurves for linear, star, H, and comb 1,4-polybutadienes from the literature are compared and found to agree well in the high frequency region, where G’ and G” exceed the plateau modulus, irrespective of molecular weight and branching structures. However, the horizontal shift factors used for generating mastercurves at the reference temperature show significant differences of as much as an order of magnitude at the lowest temperature, indicating either experimental errors or chemical differences in samples, possibly in the percentage of 1,2 linkages. A value of tau_e=3.7E-7(s) for the equilibration time at T=25'C is determined from fitting longitudinal and high frequency Rouse relaxation to the high frequency data. This value can be used in tube model predictions of linear rheology of linear and branched polymers, thus removing it as a parameter that might be adjusted to obtain a fit of various tube models to lower frequency data. Variations in the plateau modulus and the entanglement molecular weight with small changes in 1,2 content can lead to large variations in terminal relaxation time predicted by tube models for long-chain branched polybutadienes. However, these small variations in the plateau modulus can be inferred from the dependence of shift factor on temperature, allowing all three tube model parameters to be obtained from high frequency data for 1,4 polybutadiene. Keywords: 1,4-Polybutadiene, Tube Model, Time-Temperature Superposition, High-Frequency Relaxation