The installation is not plug-and-play. The antenna must be replaced as the ELT110-4 is a 121.5MHz only ELT. The ELT-345 requires a 406MHz-capable antenna. The ELT-345 is smaller in size so it will require installation of a new mounting tray.  However, the mounting tray may be able to accommodate the existing mounting holes. The ELT-345 connects to the remote switch via a D-sub connector instead of the molex plug used by the ELT110-4 so, rewiring and connector change is required. The remote switch needs to be replaced with the remote switch included in Kit 8107. However, the existing may be reused for the new installation as the ELT 345 requires only 2 wires for the interface to the remote switch. Optionally, one additional wire is required to connect the ELT-345 with an onboard GPS for position data to the ELT. If this is desired, the additional wire may be available from the existing installation as well.