I believe In the silverado door panel the steel mesh that surrounds the speakers should easily pop out with a flat head screw driver, then if you unscrew the four screws around the speaker you can drop them out threw the hole to work or replace them.
My 1996 Silverado Ext. Cab has 6.5" in the door panels as well as 4x6" in thee rear pillers..
It has 4x6" speakers.
They are 6 1/2 inch in the front door panels. If its an extended cab the rears are 4 x 6 inch. Let me tell you from experience replacing the rear speakers in a 97 extended cab is a pain, but can be done. Be cafeful not to break the panel clips then your panels will vibrate when the speakers are turned up.
well 6 3/4 front doors and 4x6 on back door panels according to schoche website
Front Door Speakers are 6-1/2"
4×6
For the front speakers your gonna have to take the door panels off to get to all the wiring and everything and for the back ones you should just be able to take the plastic cover off and replace them
Chevy speaker size1988 has 4x6 in both places.
In a 2000 chevy Silverado 1500 z71 the front door speakers are 6.5"
1500
the dash panels just pop off but you will have fun getting the switches off
The parts should fit.