Does normal 6x9 speakers fit 96 Toyota Camry rear?

[SZ]

Hi,

I checked from the trunk and found my 96 Toyota Camry
use 6x9 speakers in the back. However, each speaker
has only 3 screws for mounting (two seems at the normal
position and one at the other longer end). It does not seem
that a normal 6x9 (such as a pioneer) can fit in the basin
since the basin at the side with one screw seems to be narrower.

I checked crutchfield and they do not list pioneer speakers as
options for the car. But for the models they picked, some
of them look similar to the pioneers. Strange to me.

Does anyone know any trick for mounting the rear speakers for
the car?

Thanks,

-SZ