Catalyst interchage?

[mrCharlie]

Stupid question-I suspect I know the answer, but it doesn't hurt to ask anyway-

 

Does anyone happen to know if I could use the catalytic convertors from a 2002 OBW in my 99 Legacy GT 2.5? Someone on Craigslist local to me is selling the entire exhaust for $100, cats and all, and I was thinking I should check it out. Yes, I know that buying used catalysts isn't exactly legal, etc, but it's the only way I can afford to replace it.

 

I am pretty sure the cat is bad on my car. I used to get P0420 all of the time, and the mechanic I took it to a while back told me the inside of the front cat was broken apart and rattling. P0420 hasn't come back for a while, but I also keep having to reset codes chasing another problem down, so I don't think it has had the chance to run the right number of cycles to test the cat.

 

I do have a scan tool,I could reset it indefinitely so I don't have to stare at the light, and I don't like in an emissions-testing area. I'd rather make it right if I can do so affordably, and get rid of the annoying rattle from the broken cat I have now.

 

Thanks!

[mrCharlie]

I just found out it's been sold. Oh well...feel free to reply if you happen to know, might help someone else with the same question in the future.