Dave, the 56-57 fog lamps are identical (but 12V) to yours. The first time I tried to install a new bulb in the socket was not very positive: the glass part turned and cut the wires. One bulb less! I did differently the second time: I took the reflector out of the lamp assembly and, from behind the reflector, I pushed the 3 pins to allow the socket to engage properly and could also turn it without to have to put too much force on the glass. I recommend this practice to every one who ask how to remove and install these bulbs. If the bulb would costs $ 2.00, it would not be a big deal to destroy one, but at the price they are sold now, its better to be careful!
Im not sure, but I suppose that there was a special tool to remove/install these bulbs.
Good luck,
Roger