It's the two raised round little side prongs on the metal part of the bulb that go into the socket that are giving me the problem. The prongs are straight across, but the factory bulbs are slightly angled. I can put the bulbs in, but because of the prongs I can't push and turn the bulb to latch it in.

For the front turn signal sockets, I can't even get them to go in the socket at all. Very strange.