[Arran]

Hello Again;
  I had a look through the Rider Manuals I have from 1935 to 1942 and whilst Gilfillan did manufacture some car radios, and did use some 2.5 volt AC tubes in some of their AC models, I couldn't find a single car radio that used 2.5 volt tubes, let alone a mix of 2.5 volt and 6.3 volt tubes, nor a mix of those and a 0Z4 cold cathode gas rectifier tube. All seemed to use 6.3 volt tubes, and maybe an #84 rectifier (basically a older six pin ancestor of the 6X5) I did not look at their post war sets however. I also looked in a reprint of an RCA book put out a set index based on tube/valve socket layouts, there was even less in it then the Riders books under Gilfillan, maybe six sets in all, and only one car radio. If you could post a photo or two that might help, assuming the ###an Bros was not the manufacturer, and not a dealer or importer.
Regards
Arran