96 850 GLT Catalytic Converter

Hello All

I have a 96 850 GLT wagon. My exhaust started making a growling noise
that made me think I had a loose heat shield. I took it to my trusted
mechanic and it was not a shield but the insides of my catalytic
converter are loose and rattling around. My mechanic advised me to
replace it as it could cause engine damage.

I looked on several sites and found converters but I have no idea how
to tell which one fits my car. For example:
http://www.car-stuff.com/catalytic/quote.php?make=30&year=1996&model=682

This site lists several ranging in price from $50 to $400. I
understand that direct fit means that the old one can be unbolted and
the new one bolted in. Will the $50 unit work as well and just need to
be welded into place?

Which one is right?

Regards
Russ