So i tried to do some reading and got mixed results. I have a 97 z38 (30th) hard top. I cant figure out (without pulling off panels) what size speakers are in the back seat, and in the trunk area. Also how many ohms are they?
I replaced my door speakers(originally 2 ohms) with 4 ohm polks (6.5) and with the 2 wires that went to the tweeters on the oem ones i wired them to a kick panel i installed (a 2in and 5 3/4.) It sounds way better, Im pretty proud, i didnt break anything on the door panels too.

 

my rears were same size as the front. i use crutchfield to figure the corrrect size. you punch in the car you have and they telll you what fits.

 

so 6 3/4 in back seats and 4in in the trunk area? whys the cove in the trunk so big then?

 

make sure its quoting for the right system in your car. i only had one sub in back and it was tied into a amp. i took both out and replaced with a thunderform subwoofer.

 

what size speakers fit in the factory holes on back?

 

my 97 vert 30th has 6 1/2 front and back

 

mine had 5 speakers stock, the four 6 1/2 and a woofer on the driver side in back. i believe the op has 6 speakers in the system. crutchfield calls for 4 inch for them or it if its 5.