Yesterday I tried to install H&R lowering spring on my 2002 legacy GT using KYB struts. I had no problem putting on the rear it was the front I had a problem with. I now know I need part number 20323FA000 which is a new spring seat for the front springs. That is because the H&R springs are more narrow than the OEM springs. My problem is that on http://www.subarugenuineparts.com it come up with 6 different parts. 5 under collision catalogue and 1 under OEM. I am not sure which one I need. Can any one help me?

That part number is correct and you should probably just call them and verify. Sometimes the same part and corresponding part number is listed in various sections in a catalog. That makes the catalog longer, but easier to navigate since you may need that part for different purposes.