Note the handdrawing on the schematic.  First attempts on traditional current limiting can be seen.  This was soon discarded. Note also the extra resistors near the output.  The loudspeaker was to be coupled between the output terminal and the small 0.1 ohm resistor to ground.  This was a later idea (don't remember when it was introduced) which would give some current feedback in addition to the traditional voltage feedback.  The effect would be to make the loudspeak "invisible" to the amplifier.  I will come back later to this - <here>.

Note that you can see the prices on the transistors here, NOK 4.70 in qty 100 for BD203/204. Cheap transistors !