Try JWS I think they've got a few, there are 2 different sizes for classic shaped Impreza's that I know of, best to measure the gap & see if someone here has one the same width, you might even find the Liberty/Legacy one fits too.

__________________
Beaten up old 98 Gen 2 Liberty, 13.0, stock V3 STI running gear.
07 Transit motor home
69 VF & 70 VG Valiants needing full restoration
Yamaha Zooma 50cc rocket hopefully going with the Transit.