[Arran]

Russ;
  I noticed that the twin speakers in your console have the exact same numbers stamped on the backs of the rear brackets as the tombstone that Fred has. On one the number is 01525, and the other has the number 01526, the latter has a terminal block and cover mounted to it, so I would assume that these are W.G factory part numbers. Also these numbers are obviously related to the twin speaker models since Fred's tombstone has speakers of the same construction also with 01525 and 01526 stamped on them, again the one with the 01526 has a terminal block and cover mounted to it, but the part number used on the speaker in your tombstone has no terminal block and has a different number altogether C-1963. Without comparing circuit diagrams I would guess that the field coils of the twin speaker models are connected in series whereas the voice coils are connected in parallel, so you probably couldn't swap in a pair of speakers from some single speaker models without changing the circuitry, again this is only a guess since this is what was done on a twin speaker Electrohome set I am working on.
Regards
Arran