rattling reverse on an 03 diesel auto

Hi everyone, my lovely 03 TD4 Kalahari has started to rattle in reverse, forward is near silent and car drives fine with gears selecting as they should. It started straight after I fitted new intercooler hoses! No, all tools are present and correct. TBH it sounds suspiciously like a tired bearing, or a bearing running dry.
Any ideas gratefully rec'd cos I don't understand this one, thanks