won't a 1999 Outback resonator fit a 1999 Legacy? 

 

the following listing says it fits the outback but not the legacy - they sure look the same, maybe the attach point/hanger is slightly different but i don't care about that:

 

http://www.amazon.com/Walker-55180-Resonator-Assembly/dp/B000C93ESO/ref=sr_1_34?s=automotive&ie=UTF8&qid=1431707891&vehicle=1999-13-64------------1-0&sr=1-34&ymm=1999%3Asubaru%3Alegacy&keywords=exhaust

It depends, do you have the 2.2L or the 2.5L?   The outback, IIRC, came with the 2.5L while the legacy was still available with the 2.2l.

Ha ha, you caught me - I Intentionally didn't say it is a 2.2 hoping someone would say why/they've tried it rather than "no it's a different engine".

Do you know why an EJ25D resonator/mid section won't work on a 99 2.2?