हम हवाई जहाज़ उड़ाने वाले, फिर भी फ़िदा हैं, पटरी में दौड़ने वालों पे. - SK Mangla

most of them have common model designs!! so can b distinguished by looking at their names or else the road numbers. well many pple aren't aware of road numbers i.e 20045 which identifies as the road number of the specific loco. so when the loco approaches towards us, the name WDG-4 will b written on the hood or near the buffers.
WDG-4's n its family can b recognized easily due to its heavy humming engine sound from a distance of 1-2km itself.

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