In this paper the performance analysis of signal-to-interference ratio (SIR) based Selection Combining (SC) diversity system over alpha-mu fading distributed and correlated channels is presented. Formulae for the output SIRpsilas probability density function (pdf) and cumulative distribution function (cdf) are derived. Also, the results presented in the paper include all important scenarios of triple SC diversity systems, which is main contribution of this paper. Analytical and numerical results are obtained for triple SC pointing out the effects of fading severity and correlation on the system performances.