  We examine possible pairing mechanisms of superconductivity in PuCoGa$_5$
based on spin-fluctuations or phonons as mediating bosons. We consider
experimental data of specific heat C(T) and resistivity $\rho(T)$ as input to
determine a consistent scattering boson with the superconducting transition
temperature of 18.5K in PuCoGa$_5$. Irrespective to the type of boson, the
characteristic boson frequency is found to be $\sim 150 K$ from the resistivity
fitting. The spin fluctuation model is most consistent with the experimental
resistivity, successfully explaining the anomalous temperature dependence
($\sim \frac{T^2}{150 K +T}$) at low temperatures as well as the saturation
behavior at high temperatures. Assuming that the pairing state is non s-wave,
the large residual resistivity $\rho_{imp} \sim 20 \mu \Omega cm \sim 120 K$
suggests that an ideally pure sample of PuCoGa$_5$ would have a maximum T$_c$
of 39 K.
