Doubt it. Every catback I've seen for sale is either for 94 & 95, or 96-04.. with a few exceptions (96-98 cobra, 03/04 cobra, etc.)
Although I haven't personally been under a '98 to look at it, I'd assume since they are different drivetrains that there are differences. I suppose you could always just try it and see for yourself though..
its might fit, it depends on the joint with the Hpipe, it might be slightly different on the 5.0, but I would ask summit racing, they have a tech team that can help you for free