For the ones who have the factory theft deterrent system, is it possible to tie a LED into the light that flashes on the dash when the system is armed? I want to put a LED up where it is visible without having to get close enough to peer in the window.

 

Actually, all Ford vehicles have that flashing light. It is part of the passive anti-theft system that all Fords have (you know, the ignition key with the micro-chip in it). The factory alarm system does not have an indicator.
I have not looked at the circuit board very closely on these new stangs. I'm not sure if you could run an LED off of the theft light. Hmmm. Interesting idea though. Where would you mount the additional LED?

 

I believe that light flashes based on a signal from the SJB and/or ECM. Last time I looked at the back of the guage pack it had, I believe, a connector for a single ribbon cable. As such I don't think there'd be an easy way to connect to the indicator without actually communicating with the onboard computer.

As an alternative you could always do what I did. I had the aftermarket installer install the LED in the inside plastic (drivers side) A-pillar. Now you can see that sucker flashing half a block away!!!

 

Up in the a pillar is what I had in mind. I mounted one up there in my truck but it had an aftermarket alarm with an actuall led on the dash so it was easy. I just want it to show up from a distance so people know not to mess with it. The one on the instrument cluster is really hard to see.