Hey guys I don't know how to use this website sorry if I'm not in the right area but can anybody tell me if a 91 pickup door will match up with a 90

 

Yes. Also, just use Google. The results will lead back here anyway.
Check the site car-part.com as well. They are a salvage yard database and will allow cross ref years.

For a little more shipping, you might find a door that matches your color, so no paint work. Good luck