You can try to get a "direct fit" unit from a junk yard, but get a guarantee that it will pass emissions or your money back.

Otherwise, the most bang for the buck is a "universal fit" unit from any of the discount parts houses or even from a muffler shop. Match the inlet/outlet pipe size and make certain the hanger arrangement will work. Some of them are welded in and some have slip fittings with clamps.... just know if you're going to do the work yourself that you might have to do some fabricating (check the fittings to see what will work). You can buy them from $40-200, depending on quality.

Type "universal catalytic converter" in your web browser and you'll be entertained for a while and get some ideas.

Frank