The red arrows point to where there are two hidden screws that hold the speaker cover in place.  There are also some prawl clips on the underside of the speaker cover.

New speakers were four inch Blaupunkt PCxb402, 2-way, that I ordered from Crutchfield.  The new speakers were supposedly drop in replacements for the stockers. 

The new speaker required a little bit of grinding on the metal edge to get it to fit in the passenger side.

I think the opening in the dash was a little warped from age, so the fit was prob not the fault of the speaker.

Frankly, the new speakers did not sound that much better, but I think that had more to do with my head unit, which was an OEM replica AM/FM casette made in Mexico.