Nope never found a speed bleeder. I did find a catch bottle with a one way valve in it which I've been using instead for one-man bleed jobs. Bonus is it was also cheaper than a set of speed bleeders.
I get 10 of the clear bodied plastic ones and some air line together.
Heat line w lighter to open up to fit brake bleeder.
I have an aerosol can of alcohol(circuit board cleaner isopropyl) to spray clean out check valve and reuse. Can also just throw away as needed as brake fluid kills the plastic.
I have also bought these in walmart and pet stores.
Another option is the motive power bleeder(I use the metal red cap...should be the european adapter if I am remembering correctly). It's what I use on all my cars and has always worked well. I previously used speed bleeders, but have seen a few fail over the years on ppl's cars at the track so I picked up the motive power bleeder just for my own piece of mind. I'm sure they were probably operator error, but not worth the additional potential point of failure for me.
I cant believe this car has been out for 4ish years now and there hasnt been anyone to figure out the bleeder size. I too am looking for a speed bleeder but I suppose Ill just let my wife help and listen to her grumble at me. Another thread here was never answered. https://www.mustang6g.com/forums/showthread.php?t=79452&highlight=bleeder
I went with a bottle with a built in check valve for $10 instead of speed bleeders and I then later to a motiv pressure bleeder, which IMHO is far superior because you can watch the corner you’re bleeding and more easily spot bubbles instead of doing it blind with the speed bleeders. Knowing whats coming out of each bleed valve is worth more than 6 costly replacement bleed nipples and doing it by blind guesswork. Live and learn.