1994 Nissan Maxima rear spkrs

Could anyone out there give me any help on removing/installing rear deck speakers in a 94 maxima. I couldn't tell if they are removed from the bottom of the deck in the trunk or from the top by just removing the grilles. It looks to me like the grilles are screwed on and don't just pop off. But I couldn't find any screws from inside the trunk. Hope this isnt a dumb request but I couldn't really figure this one out. Oh yeah this is a non Bose system, if that matters. Also what size speaker would you recommend for this location. From what I can tell its either 5 1/4 or 6 1/2???

Thanks for the help and I enjoy soaking up all of the info you folks share on this site.

Update for anyone who may need this info. I guess this was a dumb question or everyone else was just as lost as I was.

I just layed in the trunk for awhile and figured it out. The rear seat back needs to be removed to get the rear deck out.  You have to unscrew two screws behind rear seat armrest then remove the third brake light. Then push out the three white plastic tabs from inside the trunk, right behind the seat,under the deck and push the seat back forward. After you pop out the green clips from the bottom, the deck will slide out and there you go. Hope this helps someone.

Later folks, off to my next challenge.