The factory hole size is 5x7/6x8. Many people incuding myself have put 6x9's in all four doors. Some 6x9's can drop right in but others may need new holes for the screws or a lil shaving of the factory hole.
Anything below he factory size you can make an adapter out of mdf to accomidate you speaker so it will fit the factory hole.
All set now?
