did the subfrabe that you had replaced look anything like the one in this ebay auction??
http://cgi.ebay.com/ebaymotors/SUBARU-WRX-STI-REAR-SUBFRAME-CROSSMEMBER-2005_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem200316735596QQitemZ200316735596QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories
http://cgi.ebay.com/ebaymotors/SUBARU-WRX-STI-REAR-SUBFRAME-CROSSMEMBER-2005_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem200316735596QQitemZ200316735596QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories