Each of the doors have 3 Philips head screws in them.
1 you can see clearly on the inside as you open the door 2 on the inside door handle and 3 inside the arm rest.
Remove them and you can gently pry the internal panel off unclipping the pegs.
Remove electric window and door light connections and you have full access to the speaker. Should be 6.5" in the front.
Cheers.
p.s: seen this same question at least 4 times before on this site.
5 1/4 per crutchfield.com =============================== My Diamante had factory 6.5"
3 bolts 2 wires
about $700 to $800...with a new water pump
the oil filter is next to the oil pan underneath the car( passenger-side)
i do have the picture for this diagram but i can not posted if you nned ut mail me and i will send it to you .....paulcastillo25@yahoo.com
Use a chainsaw
pray
If you are inside the car, it is on the right side of the steering column, below the column. Feel with your hand as you can not see it sitting inside.
boi bangs
grundle
Remove the wiring harness from the back of your 2003 Mitsubishi Eclipse alternator. Loosen the alternator tensioner bolt. Remove the alternator belt. Remove the alternator retaining bolts. Reverse the process to install the new alternator.
There is a very good tutorial here: http://demonaudio.co.uk/tutorial/mitsubishi/colt/howtoupgradeamitsubishicoltstereo.aspx