Trying to find the muffler is like finding an honest politician. Anyone have an extra laying around or a source?

They are as scarce as hens teeth. I proably bought the last exixting nos one on the planet back in April from Hippy's mc in Kentucky. Just keep looking and make it a near obsession that's what I did to get the three I have over the last 3 or 4 years. They do exist, but they are rare. Just don't stop looking. I wish I could help you more. There is a guy that makes new pipes, I was in contact with him about making one, then he would have the patterns to make more, but he said to contact him in the off season. The guy that makes them for the mx250 sent me to him but I deleted it all. Sorry.
Charles

I found a solid one from one of my Ebay guys. It's for a 72 and I have a 74, but my buddy across the street has a muffler shop. I think I can get it to work. Any idea of how different they are? Also, it looks very similar to the pipes on my early 70s Yamaha dt-250 (long gone).

The problem with the 72 pipe on a 73/74 is that there is no cut away for the frame down tube. I had a 72 pipe in near mint, sold it on ebay for 165.00, but it was very nice. I bought it thinking I could adapt it, that was in the beginning. I held on to it for 2 years, thinking about modifying it, but it was too nice to butcher up. I eventually bought a 73 pipe that had been bracketed to fit 72 and had been welded at the header to muffler junction that was in very good shape, I will have to probably have to cut the welds other than that it looks good. then I bought the nos one. and I had another one from a bike that I bougth to rebuild. That offset for the frame tube is going to be your buggaboo on the 72 to 74. Keep looking. IMHO the sx is the better looking between the ss/sx 73/74. But overall I like the looks of the 72 sx but no electric start/down tubes.
Charles

any chance you have a picture of the front and back of the 74?

I bought the 72 exhaust. I am confident I can modify it. I'll post photos.

I can't post them they are too large. I could email them though, pm me with your email address. Charles