The front factory speaker is a 5 1/4". The steel should be scored from the factory to allow for 6" to 6 1/2" aftermarket speaker if you want to cut the hole out. The rear also has a 5 1/4" stock speaker. The mods for getting a 6 1/2 or 6x9 is a little more involved than the front.
5.25 inch
I am pretty sure they are 6x9
Begin by removing the dashboard speaker covers on your 1989 Chevy S 10 Blazer. Remove the speaker retaining screws. Remove the speaker wiring harness. The speakers will come out.
go to www.google.com click on images and type in 1989 jeep comanche multiple images will appear
The quickest wat is to directly wire the speaker to the radio. Buy some speaker wire, make sure you keep the - and + strait and connect the two right (one in door and one in the dash) speakers to the right/front wire on the back of the radio and do the same for the others, the back will have one speaker each to it.
i own a 1989 Honda civic dx and that's 5 1/4th inch door speakers as well as rear. who knows they may of not changed it
Metraonline.com, Scosche.com and crutchfield.com are the best places to find out this answer.
Stock is a 6 inch ROUND speaker. I took mine to a speaker store and they sold me 6x9's so I had to do some cutting.
6.5" front doors, 6" x 9" rear side sorry those sizes are for the 1989 pathfider...
Right Front Speaker (+) Green Left Front Speaker (+) Pink +12 Volt Ignition Wire Gray +12 Volt Battery Wire Blue w/yellow stripe Right Front Speaker (-) Blue Left Front Speaker (-) Purple Ground Wire Black Right Rear Speaker (+) Red Left Rear Speaker (+) Black Right Rear Speaker (-) White Left Rear Speaker (-) Yellow the ground(black) is on the bigger harness
The Corsica is 4 x 6 in the front and 6 x 9 in the rear
The largest speaker that will fit in the dash is a 4"x6". Not sure what the exact dimensions are on the OEM speaker. front speakers are 4x6 and the rear or 6x9