I wanted to make a custom speaker enclosure for the front doors on my 88' 90 like these: http://diverse.freepage.de/cgi-bin/feets/freepage_ext/923334x204A/rewrite/carhifi/Doorboards.htm , these are in an 80, and the guy told me that the doors are different so i couldn't make this for my 90. I do not see why and how the door structure would be different between the two cars. Are they? TIA