If so I don't believe there is an O.S. equivalent. I tried looking for those years ago and found nothing that matches up with the O.S. engines.

The Tower engines were made by the same company that made them for GMS so I often used their stuff or substituted Pitts style GMS mufflers or made my own extension. Someone with a mini mill could knock one out for you.

In your case you want exactly the same spacing as the GMS .76 engines.

John, can you measure the holes on your muffler center to center. I was working on a project and thought I would need an extension and fabricated a couple. One fits OS .61 FSR and the other OS .61 SF. Both are about 1/2" thick, if either would work I would be more then happy to mail it to you.

Also note you'll need the exhaust hole rectangle dimensions as it is no where near the same size as the O.S. engines.

I will measure them tonight and let you know.
Thank you!!

I just did a little research, looks like the bolt holes are 42mm spacing. Looks like I have one in my parts bin. Didn't realize you were just on the other side of the river. I'd be happy to meet up and get this to you.
https://cimg3.ibsrv.net/gimg/www.rcu...f0cd9db919.jpg

Cool , Yes you are on the other side of the river. Where do you fly at? Skyknights?
I'll message you my number and we can go from there...

Replied your pm.