I can only speculate, but that is exactly the reason to ask here. Repairpeople must have coffee cans full of these from all the b&s replacements they have done. For a lot less than buying from the mfr, and a lot quicker.By the way, why didn't you consult the manufacturers of the tuba that you're repairing? Sounds like a pretty common part to me
Dale, I have some Alex S links from a 151 euphonium, if they are of any use to you.
Dave