Pre-Owned 2D-142-002 Class 142 Pacer Merseyrail 2 Car DMU No.142042Pre Owned Item, in as new condition. Test Run. The British Rail Class 142 is a type of diesel railbus multiple unit designed to run in pairs for use on branch lines in Northern and South Western England and North Wales. Ninety six of the sets were built by BREL at Derby between 1985 and 1987 and followed on from the design of the Class 141. Initially, the Class 142 exhibited many operational problems including the inability to negotiate tight curves,