beez - The US spec radios are different from OZ-spec radios.
- OZ-spec AM jumps in 9 kHz steps, not 10 kHz
- OZ-spec FM jumps in 100 kHz steps, not 200 kHz
- de-emphasis for FM is also different, but let's not get into that....
I had a TD-6146 in my ex-US market 780 (1 of the 2 in OZ) and couldn't tune it in to most of the stations I wanted to listen to, so Craig Rasmussen (SA Volvo Club) swapped the 6146's faceplate onto a CR-825 (i.e. OZ-spec CR-815).
AFAIK, the TD-6141 and 6146 are the same (Alpine) unit with a different faceplate. Do you need the 6146's faceplace for fitting into a 780? My 6146 now has the 825 faceplace on it - 825s were standard OE on 940s here.