Apparently, 11/16"-24 is a less common threading pattern.

Silencerco's Alpha direct thread mounts don't list one.

Are there any other sources of a direct thread 11/16"-24 mount that will fit my Octane 45K ?

What gun is it for ??

A quality thread adapter will probably be your best bet. Rocksett it onto your barrel and torque down to 30 ft/lbs:

https://www.cncwarrior.com/Thread-Adapters-s/1949.htm

https://www.thesilencerstore.com/category-s/149.htm

A direct thread mount or piston mount made for the Octane would be the best option (probably not available). If that is not possible then a quality adapter would work. I have a couple of adapters from TROS in Oregon trosusa.com The make good quality stuff.
I’m curious what gun and caliber uses the 11/16”x24 thread pattern?

Ruger 77/44

I second TROS. He has made a couple if things for me over the years that worked perfectly.

Might want to check here as well...

https://diversifiedmachine.us/shop/

I haven't personally used him, but from what I've seen on a couple of other forums he's good to go. I didn't see your necessary thread pitch listed, but they offer a custom threading option.

TROS has been my usual go to thread adapter--no love for the 11/16 oddball tread.
https://trosusa.com/suppressor-thread-adapters/

My new go to for thread adapters is Hughes.
11/16 in stock.
https://hughesprecision.com/pr.../accessories/page/3/

Thanks for the suggestions, guys.