NOS Echlin DS40 dimmer switch listed to fit:
Buick 1934 - 58
Cadillac: 1934 - 58
Chevrolet: 1929 - 54
Oldsmobile: 1928 - 58
I have 4 for sale as you can see in the picture, the price is for each one. As you can see, one is missing the screws, so it will be the last one sold.
Never installed, from a dealership that closed it's doors in 76.