You don't need new brackets. You can bend your original bracket enough to accommodate (if you're still 6v) a #81 tail light bulb and a #1129 stop light bulb in the upper socket. Stock configuration was #63 TL and either #63 or #81 stop (both bulbs light on stop). The problem is the #63 is a 3cp bulb and the #81 is 6cp so not a lot of light is emitted during braking. By bending the bracket you can make enough room in the upper socket for the #1129 which is a 21cp bulb. There are 12v equivalent bulbs but I don't know the numbers. Now to answer your question I believe the sockets just press in.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.