To those who are interested ..found it out! 😃
I've two Logitech Wingman Extreme Analog, made in Taiwan and made in the USA.
The cable colors and their button assignments of both are identical.
The wiring harness from the handle has the following button assignment:
Grey = Button 1
Orange = Button 2
Purple = Button 3
Red = Button 4
Yellow = GND
Easy modification, great fun.
'Tailgunner', 'Starhawk' or 'Star Wars' f.e. plays fantastic with this joystick.