Can anyone tell me how I get to the 6*9s in the back deck of a 99 grand prix?

Well in buicks they are held in from the underside with some plastic spin on nuts.four of them on each.And in 92-99 bonnes they are held in from the top with a plastic retainer plate the speaker screws to then snaps to the deck..I would assume on of those two is how its held in.

Ive looked under the deck in the trunk and dont see any visable nuts, or clips.As far as on the bonnevilles I replaced mine by takeing the mesh grill off and and simply dropping in a new speaker but this grand prix the grill dosent just pop off and I dont see anything from the trunk holding it on.

just asked a buddy of mine on facebook whos an audio installer and heres what he said

you can't remove the speakers from inside the trunk; they're top-mounted on the rear deck. You gotta to remove the entire back seat start with the lower cushion,.then you'll see the bolts underneath that hold down the seat belts and rear seat back. Remove the bolts and pull up on the rear seat back to unhook the top section and remove it. Afterwards you'll need to pull off the side panel on one side; then you can pull the rear deck cover forward and remove it. The rear speakers are mounted on plastic holders that are just clipped into the rear deck....

Ya just got off the phone with a buddy who works at best buys audio install and he said the same thing, said it was a pain in the ***! Well thanks for the help it is greatly appreciated.

You don't have to remove the entire back seat if you have ones that fold down. I don't recall if the grand prix had seats that folded down or not... If they do, you can get the rear deck pad out of there by just unbolting part of the rear cusion and bending it back just enough to allow you to pull the retainers out. After that, lift it up and slide it out. I did this on my wife'* 2000 Regal GSE earlier this year.