I have three questions here. Usually a diesel loco's class number represents it's power rating. For example, WDM 3A is 3100 HP, WDP 4 is 4000 HP. But these locos are obviously not 6000 HP, cause probably that much powerful diesel loco doesn't exist in the whole world. Then-
1) What does this class number 'WDM 6' represent?
2) What is the power rating of these locos?
3)...
more... Why these locos are used in shunting only despite of being WDM class?