I've been doing some research on the site, but haven't found much yet. I've HEARD that in the non-Bose edition for (at least) '89, Nissan had some type of physical adapter or plate that made it possible to mount the non-bose 4X6 speakers in the front doors. Is this correct? (I assume since they didn't make two different doors!)

I have an '89 WITH the Bose setup and the speakers are heading south as well as the headunit. I'm going to order up some 4X6s for the front if there is indeed a type of adapter as I don't want to have to make something if possible.