Hello Chris,
I don't understand 0.383", the diameter is 3/8" Whitworth (9,70mm) and has right 28 threads per inch.
The same, what do you mean 0.518 ", the diameter is 5/8" Whitworth (13,05mm) and has right 18 threads per inch.
Sorry, but I'm not very learned with the various british standard. I thank you if you could confirm the threads are right 1/8" BSP and 1/4" BSP.
On the continent, the autojumbles have not much british tools or others. Do you know a specialist suppliers on the Web ?
Thank you for your help.
Michel.