Harsh,
Are you talking about transaction VL06L - Outbound Deliveries for Loading?
The screens included in this transaction are customizable, but I do not see any option for adding in DG type data. This most likely is becuase of what Christoph mentioned above. UN numbers can change based on DG reguation.
But, if you select the delivery and click "Item View" you can add fields. Here if you choose Settings > Layout > Change you have options that you can add to the display.
If you truly want to change this display, I would think ABAP enhancements would be needed.
Hope this helps,
Eric Perala