I used one of these:

http://www.crutchfield.com/cgi-bin/S-qkrZGTcrlrA/ProdView.asp?s=0&c=11&g=752&I=120999000&o=m&a=0

It's a universal underdash mount. I didn't put it in the stock radio location because of complications in getting a DIN-sized radio in and out of that small space. Instead I'll be putting a bunch of guages in there after I pull the radio out.