Earlier cars have variants of the awfully fragile and exposed PCB as an early form of BCU. This allows the possibility to replace with basic relay control as Rog has done, although I believe without any timers. I think I'm right in saying the logic required within the PCB to provide the momentary switch latching is lost in such case hence need to replace with simple toggle switches. Perhaps Rog could confirm but if so it appears that Borghi offers similar as his version appears to employ retro toggle switches as well.
I will try and answer Richard. Not sure what timers you are referring to but the rear fog light was the only one of the original four vending machine switches that had a momentary action with electrical latching. My new fog toggle switch work similarly. The fog relay is powered by the side light circuit so the fog can only be on when the lights are on. The toggle switch also has a LED warning light to remind you when activated.
