[overrestored]

found it... it is the DSP or digital sound processor plug... for a rare(ish) accessory in the door panel that nobody really likes... and one that really doesn't do much either according to what I've read up on it...

Here is a link to the bulletin on it:

http://www.pcarworkshop.com/images/b/b6/9161_1995_690495geolab.pdf