Another brake light question and a new one about my headlights

[ghostvbhc]

So, today I replaced the headlight bulbs and we thought that's the reason the headlights weren't working, but the high beams were working. Now again my high beams are working (and, they turn off after five minutes and turn back on after about a minute or two) and the regular headlights aren't working again. Also, my brake lights stopped working again, both of them this time with the lights on or off, but the blinkers work. Can anyone help me with these? I thought I figured out the brake light problem because they were both working just fine and now today they aren't working at all. Thanks to anybody that can help.

Oh and also has anybody hooked up a third brake light to a 69 c10? I bought one, but we don't know how to hook it up.
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