Did a quick search for "USDM SVX VTD" and NASIOC came up.
http://forums.nasioc.com/forums/arch.../t-215493.html
mbtoloczko01-14-2004, 05:42 PM
Folks, as someone said in an earlier post, the USDM SVXes have a clutch type computer controlled center diff. The non-USDM SVXes have the VTD center diff with the planetary gears that is shown in a picture in two of the earlier posts. The WRX was not the first Subaru to have the VTD. It may have been the first USDM Subaru to have it though.