Has anyone ever tried the aftermarket kits from Valeo/Sylvania from their aftermarket division, xSighting Lighting:
http://www.xsighting.com/
http://www.xsighting.com/products.html
These guys do a lot of Ford and GM OEM stuff, including I think the lights on the GT500 and other mustangs with HID's
They have several different kits for both 7" and 5 3/4" round replacements.