Car parts for GB.

Hi guys, first post

I have a 2000 Subaru Impreza Rx and was wondering any sites I could use to get parts?

And also if any of the GC/GD etc. Parts would fit my car? Am struggling atm, bought struts front and Rea for a Gc8 and they don't fit the car.. Thought they would and the post said it would..

Any help would be appreciated, cheers