on my 1990 there is an O2 sensor up front ,inthe downpipe but nothing after the cat..

Newer cars have a 02 sensor that checks if the cat is working. i htink its designed ot make you spend money and worry about stupid idiot lights so you run to a dealer.

If it doesn't have any other sensor after the cat. I'd replace the cat with some exhaust pipe. bypass it.

if you need to pass a smog test, that might be needed in california, here in BC Canada it was omitted and we did have a lot of cat thefts.

the cat wont affect how the car operates, unless it plugs, or unless there i a sensor that measures OT to confirm it works. I've taken and knocked the porcelain honeycomb guts out of them before as it started to rattle.. a plugged mufflersystem is a funny thing to troubleshoot because its not the first thing you really even think about.

I've never owned a car new enough to have ABS or more than one cat or airbags so I'm of limited help in what changed by 93
i did put a new one in my 1990 240 once, because it needed to pass the smog test.