I strongly recomend the following pioneer speakers. $65.00 a piece and a perfect fit behind factory grills.
Rear speakers, TS-A6880R 6x8 four-way speakers:
http://store.yahoo.com/millionbuy/piotsa6880r.html
Door speakers, TS-A1767 6 3/4" three-way speakers:
http://store.yahoo.com/millionbuy/piotsa1767.html