This paper deals with the study of stochastic modelling of a system having two non-identical class of units. The whole system consists of two class L1 and L2 respectively. First class consists only one unit where as second class having two identical units. The whole system is used to process the jobs. Jobs are first processes on L1 unit (class one) and then goes to L2 unit (second class). All the failure time distribution are taken as arbitrarily distributed. Using regenerative point technique, various reliability characteristics of interest to the system managers have been evaluated. Finally, some graphs are also plotted in order to highlight the important results.