If theres a dash kit in there, the factory pocket will not be in there... in its place it will be a cheap looking molded pocket and a "frame" that goes around the "sleeve" of the deck. The deck, as it is, will probably also tend to stick out of the dash a little too much.

Being theres already an aftermarket deck in there... it could just be a matter of swapping the sleeves, and sliding the new deck in. Although, thats the ghetto way to do it... as I said, they tend to stick out of the dash too much, and there is no rear support... which can make the new deck skip too easily.

If theres no dash kit in there now, keep it that way... but figure that out first, and i'll help you based on your situation.