Im trying to get some replacement speakers for my 86 T/A. I have the factory "performance sound" option with the gain switch. I mesured the speakers in the sail panal wich are 4*6 up top and 5" below those. Im trying just to replace the 5" for now but i cant find any speaker for it. all i can find is 5 1/4's. Where could i get some 5" ones? What kind are they? are they "mini Subs"? Here's a pick:

focal makes a 5 3/8" sub, but be prepared to pay the price
i.e. almost 300 bux

http://www.focal-america.com/catalog/utopia/5ws.htm

Have you tried to just wedge in a regular 5"er in there? If anything just cut the sucker to a 5 1/4".