The issue is not with the tubes but with the nuts on the tube.
The 5 bearing engine i bought did not have one in it but when i thought i could use the old one, but that does not fit either.
So i bought a new tube and lock nut which is a similar diameter as the old one but a very coarse pitch, the old one was a very fine pitch.
I think i will have to do some measuring, i was just curious if someone knew what the two different threads are off the top of their head.