Might those "TACs" actually be the labeled name for the Zones ?
Met with my buddy on the USSS today and he got his new car last week. He was in the area so I met up with him. He showed me the set up. Mot. 8550 with handheld mic with controls for lights and siren. In trunk was radio "gear" that had a 100w VHF, rest were regular mounts. In glove compartment was LTE radio with mic drilled out the back sitting on seat. No name. Mic had screen and buttons. 3 TACS. 1} new england wide secured (yes screen was green) 2} "greater" new england not secured (red background on mic screen) and 3} nationwide (unsecured). He is NOT on a protection detail except when "anyone" is in "town". On bank unit. They use LTE cause VHF not reliable in NH and Maine. Says only 10-15 guys have the radios and they only use really to talk to base in Boston. The Mot 8550 has the new triband antenna which is awesum. Compact and nice design.
He said the protection units have Sat. comms in comm. vehicles and their is a bank of motorola portables in suburban to hand out if needed.
One question which he didn't know answer to was the reason for 2 VHF antennas on Presidential and VP Limos. Knows one is for mot. radio on passenger side up front. In limo, tail suburbans (almost every vehicle in motorcade) but why the other one????? He did say it goes back as far as JFK's limo.