TubeNet

I'm looking for both the bell tenon and receiver from a Martin Mammoth.

I have a Martin helicon from the late teens that appears to use the same size bell as a Mammoth tuba.
In addition to making it much easier to transport the helicon (sousaphone style, in a bag), I'm hoping it will work as an upright option for my recording bell Mammoth.

I'm also willing to buy a whole stack if someone did a one-piece bell swap on their Mammoth and they'd like to offload the whole thing.

Thanks!