i just found these on google in a search :
416.6500 R - Suspected to Be the DEA (Heard from Beachwood, NJ) - PL 156.7 Hz and P25 Digital
173.1500 R - Suspected to Be Coming from Atlantic City International Airport (Heard from Beachwood, NJ) - DPL 412
172.5750 R - Suspected to Be the FBI (Heard from Beachwood, NJ) - PL 167.9 Hz
171.8000 R - Suspected to Be the FBI (Heard from Beachwood, NJ) - PL 167.9 Hz
168.1750 R - Suspected to Be the FBI (Heard from Beachwood, NJ) - PL 167.9 Hz
166.8500 R - Suspected to Be the FBI (Heard from Beachwood, NJ) - PL 167.9 Hz
167.1250 R - Suspected to Be USPS Trucks from Northern New Jersey (Heard from Beachwood, NJ) - PL 114.8 Hz
163.5875 R - Coming from Fort Monmouth; Expected to Be a Police Secondary or the Police Repeater Input (Heard from Beachwood, NJ) - PL 151.4 Hz
East Coast Scanning Resources • View topic - Unidentified
so i am wondering if 171.8000mhz is a commonly used FBI frequency?