Has anyone mounted an aftermarket GPS antenna in their box?
 

Looking for ideas on where / how to best mount one.

A good place would probably be along the bottom of the windshield, or in the A&B pillars. There is an opening of just enough space to shove wires into the pillars out of sight without taking them off.

I ran mine out through the fire wall and secured it to the bottom of the plastic cowling covering the windshield wipers. Took it to the passenger side so the cable was clear of the mechanism and is hidden from view.

I mounted mine under the here.....

http://www.renntech.org/forums/uploa...1124727841.jpg

I just did this on my 99. I mounted it in stock location but what a PITA! Obviously they mount it at the factory BEFORE the windshield goes in.
The cover to the infrared thingy in the center of the dash pops off.
Then you have to GENTLY pry up the defroster grills.
Then I loosened but did not remove the 2 screws holding down the infrared thingy.
Removed the horseshoe.
Put the antenna in stock location and snaked the wire down to radio.

What Chuck W. said

Yup What Chuck said. I just did it the other day. Kinda a pain but it fit perfectly.