Yes Charles there are a number of variations of these amplifiers, I have come across a few of them myself in my digging and I am sure there are more of them.
To answer your question my "BBC" types are both ex SABC and externally they look identical to most of the types which come up on the Internet described as BBC versions. The output transformers on both are reference number TL/12/T2/1B and the transformer on the third one has output transformer number TL/12/T2/2.
Of the BBC types I have identified the following variations in no particular order:-
Factory fitted heat shield between the valves and the inductors and paper capacitor block , there is no change over switch from the 600 ohm input transformer to high impedance input, no volume control and no Jones plug input or octal input socket. The input transformer is mounted where the octal socket would normally be.
No heat shield but has a volume control only with transformer mounted as above. No switch or Jones Plug adjacent to volume control.
Has octal socket as per commercial version and 600 ohm input transformer moved back close to capacitor block has Jones Plug input, change over switch and volume control all in close proximity, this is the version my two examples are.
Another version I am aware of has a high impedance output transformer and was used to drive the modulators of AM transmitters. Have not come across any photos of this particular model
Adverts in Wireless World in the 1950's indicated that the special BBC version was also supplied to the SABC and the number mentioned was 600 amplifiers, so I had always assumed the locally used versions were in fact the same as the similar looking models used in the UK
The very early production models used an EF36 input stage, later changed to EF37 and finally to the EF37A, all basically the same valve with improvements
Have not taken note of any variations in colours of the wires which you mention, I was not aware of the other variations in output transformers used, thanks for that information.