We often get calls for replacement catalytic converters, mostly because they have been stolen.

Unfortunately its not just the catalytic converter that gets stolen, they will also have taken the lambda (o2) sensors, and damaged the front and rear sections of the exhaust system.  So some level of fabrication to the exhaust is always required, and you will need new sensors.

We always recommend you dont call your insurance, they will write the car off in 90% of cases.

All is not lost, this is unfortunately a common occurrence with many cars these days due to the value of the metals inside the catalytic converter.  As such you can get a universal catalytic converter fitted, this is done by a specialist fabricator, they will also carry out repairs to the cut sections at the same time.  Most exhaust fabricators will also replace the lambda sensors, however some may not.  

We suggest you look for a local fabricator, or a Powerflow exhaust franchise near you.  Here are some handy Google search links