Quote Originally Posted by Downshift1
BE/BH Specific Parts list: (00' BH/BE GT Part Numbers)

Universal Joint Assembly 34170AE040 (Steering Coupler)
Trailing Arm Bracket- RH 20540AE000 (Front Trailing Link Mount)
Trailing Arm Bracket- LH 20540AE010 (Front Trailing Link Mount)
Flange Bolt 901000179 (Rear Cross Member Bolt)
I have some information to add to this based on my information gathering and observations while preparing to do this to my car.

On a Legacy that does not have subframe spacers, there is a washer between the subframe and the chassis. Subaru calls these the "Upper Stopper" You will need 4 of them in total.

The 2003-2004 model years have a different Trailing Arm Bracket that also includes a subframe brace. The brace is the same between Legacy and Outback, but the brackets are not.

There are also two subframe support brackets for all BE/BH cars that was not mentioned. They attach from the bottom of the subframe to the spare tire well. There are also different versions of the left one depending on model year.

These are the part numbers for all of the Legacy versions of these parts:
Code:
Upper Stopper                       20176AE01A
Trailing Arm Bracket - RH           20540AE080 (2003-2004 only)
Trailing Arm Bracket - LH           20540AE090 (2003-2004 only)
Sub Support - RH                    20157AE000
Sub Support - LH                    20157AE010 (2000-2002)
Sub Support - LH                    20157AE070 (2003-2004 only)
For reference, I have pictures of some of these parts. First is the flange bolts and "Upper Stopper"s for the rear subframe:


Second, these are the trailing arm brackets with the 2003-2004 subframe brace attached, and the "Sub Supports"