94 Sundance 3rd brake light bulbs keep breaking.

My 94 Sundance won't keep 3rd brake light bulbs in it long before they
break and burn out. I mean, it takes less than a couple of days before they stop
working. It could be even less time than this, but this is when I notice that
they aren't working any more. Is this a common problem? If so, what can I do to
keep this from happening?

When I buy new bulbs, the parts store gives me T922 lamps. These are the
same base as the dash lamps (and old miniature flash bulbs) found in most cars,
but the bulb is quite a bit larger. The top of the brake light housing is melted
above the bulbs.

And MOST importantly, is this the right group to ask this question? Any
help would be appreciated.

Thanks,
Bob