[Arran]

The proper chassis is a 38-7 chassis, the code number is irrelevant that refers to electrical revisions made on the same model chassis, like 121, 122, etc., mechanically they are all the same. The only one that you couldn't use is a 38-7 chassis intended for a chairside as the mounting hardware is different, but a chassis from any table model or sloped panel floor model will work. If there is a difference it may be in which loudspeaker was used, the 39-7 consoles would be more likely to use a 10'' speaker rather then an 8'' which is what a table set would use, I don't know which speaker the radiobar version needs.
Regards
Arran