I think I figured it out, buy actually reading the classified rules! It's not vintage, in terms of 25 years older than present.
I posted "1999" and maybe that was the problem. If you have any recommendations on who to contact for a replacement muffler for a 1999 Ski Doo Formula 380 S, that would be great. My nephew ran into a tree and fortunately only the sled was damages. I got other parts from Art's in WI and Dennis Kirk. Muffler has a kink that I assume will reduce performance. There have to be a ton of used mufflers out there.