I bought a box of odds and ends of tools yesterday and found these items in it. The two shafts are threaded the same and both have an internal thread inside the belled end. The belled end is very thin. The other end of the shafts has two opposite sides flattened, I presume for a wrench. Total length of the threaded pieces is 4 7/8 in. (125 mm).


The only markings are on the side of the u shaped piece:

I believe I've seen something like this in the past but I cannot recall where or what it was. The seller was a locksmith (retired due to health problems) if that helps at all.
Thanks,
John.