Are your speakers in the door or under the dash? I believe all NAS D90 speakers are 6 1/2 in round. So you need something compatible with that. There are speakers up to 6 3/4 and down to 5in-ish that will fit in that hole. If yours has the rubber ring that attaches to the door card under the speaker... that should offer plenty of depth. Same for the rear.
You might need to splice the existing wiring harness for the speakers if the connectors don't fit... they are the spade clip on thingys. But try first before cutting anything.
As for the stereo, I was recom'd to use this harness one by one of the site members: Crutchfield/Metra 70-9400. But I ended up going with a seperate amp so didn't need it. The wiring codes are here: http://www.the12volt.com/installbay/...tail/1252.html
if you the harness doesn't work.