Any Fiesta Mk3.5 will fit am sure as I know there differnt from the Mk3 ones from when we fitted interior in Adams car. Go to Borough Motors on Cleveland Street Birkenhead, i used to work in the garage there and I recon they'd have some. 0151 647 2000
yer they dont have to be out of just an Si, any N reg fiesta and possibly M reg may have the subframes your after, i'll keep an eye out for you around this way though