I just recently had to swap out the 3rd, aka "high mount", brake light bulb in our 2002 Nissan Altima.
It was a fairly simple procedure to install the new bulb but I took pictures of the steps and created a quick guide.
Here's the page -
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I'm sure most of you could do this in your sleep, but hopefully it will help out some of the new owners.
Cheers, Paul Michaels Ft. Lauderdale, FL