From Halopedia, the Halo wiki
Very few modifications have been made to the D77C over the existing D77H model, beyond the superficial color scheme and minor chassis alterations. The standard Pelican’s missiles and guns have been completely removed, replaced for civilian use with optical and sensory surveillance systems for the tracking and seizing of fugitives as well as addressing large-scale emergencies. For situations such as natural disasters, terrorist attacks, riots or other strategic integrations which would require a heavily armored vehicle for airborne transportation, nothing comes close in utility to a Pelican.
The New Mombasa Police Department employed their own specialised version of the D77C dropship, known as the D77C-NMPD Pelican. This variant was painted in white and black, with the front-mounted M370 autocannon replaced with a searchlight and other equipment.