Yup. I have an 02' SVT and have thought about doing the Quaife install. It's definitely something you want someone ELSE to do, and that said, will run Min. 1600.00 out the door.
Requires new carrier bearings, shims, removal and installation of tranny.
Unless you're doing serious track-time I'd stay away from it.
BTW: have you tried
www.focaljet.com for Focus boards?
A lot of nice knowledgable people there. (And a lot with SVT's and LSD's installed!)