The Kenwood FleetSync format sounds similar to Motorola MDC1200, if you have heard that before.
FleetSync can have unit ID either before or after the transmission, and send alpha numeric messages to the radios that scroll across the display screen, or a Kenwood MDT terminal. FleetSync can be used in either conventional or LTR trunked, (I also believe that Kenwood is working on it for PassPort too).
This may be what you are hearing.