Multiplex 3 (1972)
Front.
Note the antiquated sticks, non-swivelling antenna, and easily accessible crystal.
I bought this system in autumn of 1972. This was my first RC system and it was used only for model boats.
The system was new on the Nurnberg toy fair in 1972. I think I remember that MPX had two new systems that year - the other was the MPX 4.
Specs: 3 channel TX ; 27 MHz AM System (one single way stick, one cross stick)
Back view. Folded aluminium case and plastic side cheeks - couldn't be much simpler!
Here's another (from Arnout Janssen)