i have a 2000 sle how hard is it to put speakers in the rear door and what size should i use 5.25 or 6.5!

easy as any other car...i mean:
take off door panel
take out speaker
deaden
install speaker cable
install baffle
install speaker
install door skin/panel
done.

and use 6.5s or larger. 5.25s are weak sauce. just use a baffle(like you should with ANY install) and your all set.

personally if i were you i'd throw in 8'' midbasses into the rear doors to compliment your front sound stage...but hey thats just me.

oh and incase you didn't know replacing the speakers without amping them is a huge waste and you shouldn't do it. like really shouldn't do it. save up 100 bucks and buy a used 4 chan.

have fun running speaker wire!

take some pics and let us know how it comes out!

and what speakers are you going to use?

i was thinking maybe some infinity kappa'* but i like your idea about the 8'' but is there room.