I have just done some measuring today for speaker upgrade.
I assume this goes in the 6.5" speaker size category:
* speaker bracket internal diameter: 143 mm (so the speaker basket must not exceed this)
* OEM speaker installation depth: 42 mm
* screw pattern: 4 x 160 mm
* window guide 50 mm from the speaker mount plane so that's the max speaker depth with the original bracket
* there are a few mm between the door card and speaker ring where the OEM speaker has sponge for a dust seal. You can raise your speaker off the bracket with a spacer by this amount but you have to make sure the door card doesn't rattle against the speaker. A soft adhesive window/door seal will do fine. So you may be able to extend the speaker depth to 55 mm on a good day (windows guide bending not counted)
Any component speaker suggestions (fit tested)?
sold: E10 HB '96 + '97