Does look like a Hella trailer flasher unit (nowt wrong with that - I've got one). You do need to make sure that nothing's connected to the (from memory) "C/C2" connection of the relay, which drives the warning light or buzzer when a trailer's connected. Look at the cables going into the relay holder on the fusebox. Or it may just be that the indicator wiring has been "improved". You'll need to check it against a wiring diagram.
