Stock radio?

I think they can be swapped, but let me look for sure.

That doesn't look like a Ford Factory radio, at least not like any I've seen since around 2002. It looks more like a factory Tribby system, which probably plugs right in.

If the lighting isn't green, it's not a 2006 Ford factory system.

If you could pull the head unit and get a part number, I might be able to tell you what it is.

Also, if your 2003 HU has both a 24-pin and an 8-pin connector, it should work perfectly in the 2006 Limited. The pin layouts and functions are identical. But if your 2003 HU has only a single 16-pin connector, you won't be able to use it without a connector converter, and the subwoofer won't work with it.

Here are the audio connectors for the 2001-2004 models:

viewtopic.php?f=25&t=903

2005-2007 models:

viewtopic.php?f=26&t=910

The Mazda Tribute systems from 2006 were also green.

I'd be interested in the part number for that HU. [nudge, nudge, wink, wink]

Yup. I changed my '05 Escape's gauge face to a Tribute gauge face, and it was green.

I haven't seen the '08 and newer Tributes, but both the '08 and newer Escape and Mariner are now blue.