You won't find a direct replacement. The original pellet-style cats (which you can't get anymore) were huge, while the aftermarket honeycomb versions are more compact. Some minor exhaust mods will be required no matter what. I've purchased two replacements since the original burned out. The first was a Magnaflow 95509, it lasted a few years with low annual miles (less than 2k per) but the emissions gradually crept up on every test to the point I had to buy a replacement. I can't find a receipt for the second one but the numbers stamped on it indicates it's a model 80942 made by Walker Manufacturing. Not sure who I bought it from, I just remember doing a search for CARB (California) compliant cats and buying the cheapest one. Your shopping choices should be easier and cheaper being that you can install a Federally compliant unit. Magnaflow has a pretty good search function to drill down through the choices.
Being that the aftermarket units don't have the life expectancy of the oem cat and I didn't want to keep having to buy these, I had both of the cats fitted with flanges after the Magnaflow burned out. This allows me to run the old one until testing time and then the new one is installed just for the test.
You must be registered for see images attach