In addition to Troy's excellent feedback, the information below from the Wiki may be helpful as well:
Law Enforcement Unit IDs
ID#SERIES= AGENCY
100= SOUTHPORT PD
200= SHALLOTE PD
300= BC SHERIFFS DEPT ADAM,BAKER,CHARLIE,DELTA UNITS= BC SHERIFF PATROL UNITS
ECHO UNITS= BC SHERIFF SCHOOL RESOURCE OFFICER
INDIA UNITS= BC SHERIFF DETECTIVES
KILO UNITS= BC SHERIFF K-9
VICTOR UNITS= BC SHERIFF NARCOTICS
WILLIAM UNITS= BC SHERIFF WARRANTS
396 & 397= MEDICAL EXAMINER/CORONER
400= HOLDEN BEACH PD
500= OAK ISLAND PD
600= OCEAN ISLE PD
700= SUNSET BEACH PD
800= CASWELL BEACH PD
1100= BOILING SPRING LAKES PD
1500= LELAND PD
1600= NAVASSA PD
1700= NORTHWEST PD
1800= BC COMM.COLLEGE CAMPUS PD
4200= BALD HEAD ISLAND PSO
B6XX= NCSHP TROOP B DISTRICT 6
1SXX= NC BUREAU OF CRIMINAL INVESTIGATION