The part I am looking for is the one pictured.
Its got a continuous curvature on it, like a banana.
I managed to find a quality metric bolt that fit into the hole nicely, it is a M16 sized hole.
My plan is to drill a hole through the shortened bolt, and solder a copper tube to it, which I will have to bend to match the picture. It will be ugly, but it might work, and, I don't have to spend any more money on parts that don't fit.

Paul- thanks for the response, its for a Conti lever, and subsequently, do you sell your silicone seals for this piston? I was unable to find them recently.

thanks-
P

Most (all?) dipper tubes come straight and need to be bent after installation. I think it's because the threads are not consistent enough to pre-bend them.

Today, I set about to make a dipper tube from scratch.
I found a 16mm bolt, mentioned above, and it was a straightforward process of making the pipe.

first, I drilled the bolt


I filed off the top of the bolt, giving it a good place to mate with the copper pipe. Then I soldered on the pipe with Mapp gas canister, flux and lead free solder.



I trimmed the bolt down to the right length, and fit it up to see how it looked.


There was a bit of interference when I went to mount the group onto the boiler, so I ended up grinding off some of the meat around the bolt flange.
Back and forth between machine and an angle grinder outside, until it fit up flush. in the end, it looked a bit odd, but, it works. I did use plumbers tape on the threads.