Brake Light problems of the 1998 Mercury Mountaineer

The right brake light was not working. I purchased a new bulb which according to the parts book should work. This bulb would not fit into the "socket. " the only bulb in the store that would fit was a signal light bulb which promptly burnt out. I then went to the local Ford dealer and requested a bulb. The parts manager looked up the part and I got a new bulb which would not fit into the brake light socket. I then asked for a Ford mechanics assistance in replacing the bulb. He could not get it to go into the socket and he then looked up the bulb number. I was given the correct bulb. It would not fit into the socket. The mechanic then ground one side of the base's notch off so that it would slide into the light assembly so that I go home. The brake light was working at that time. I do not have the time or tools to ground a piece of the bulb base off every time I need a brake light replaced. This makes me wonder how many more non-standard parts I have on this "american made" product.