The fleet was originally numbered PWM650 - 654 in the Western Region Permanent Way Machines series .
The fleet was originally were renumbered into the Class 97 series between 1979 - 1981 .
The fleet was originally numbered PWM650 - 654 in the Western Region Permanent Way Machines series , but were renumbered into the Class 97 series between 1979 - 1981 .