Originally Posted by bertinjim

zola 1-

The 73 30 and the 75 on the lugs is the angle of the tube socket and is not useful for dating production. The centre picture is correct. Huret dropout adjusters use a unique thread at 4 mm for the hole with 0.8 mm threading. Every other adjuster is 5.0 mm x 0.8 mm. However, if you can't find Huret on EBay, then the dropouts can be tapped to 5.0 x 0.8. I've not done it but Sutherlands says it is possible.