Just remembered that I had a photograph of mine. Apologies for the quality - this is a crop from a scan of a 35mm photo, taken with a cheap fixed-focus "point and shoot" camera. I was 16 or 17 when this picture was taken (circa 1990). The original shot is here
, if anyone is interested.
The generator is the grey box. The large knob sets the frequency, and the smaller knobs would be for amplitude and waveform. The outputs are on red and black 4mm terminals, and the green one is mains earth (function generators are far more useful if they float from mains earth). I suppose a BNC would have been better, but it was a case of using whatever was to hand. A toggle switch and LED were for power.
The black box on top was a power amplifier. The kit as supplied is a bit weedy, as a TL084 can only source a few milliamps (and should have provided a series output resistor, BTW). The amplifier would have been based around a TDA2002 or similar, and was used to drive loudspeakers and motors and solenoids and similar things. A useful thing - think I still have the guts somewhere in the attic.
Some TV folk will recognise the thing on top of the DIY amplifier