Part Swapping

I am rebuilding a TR6 which is a mixture of late 69 early 70. The forks were in bits but there are a lot of new parts.
Here is the problem. The fork top cap nut and damper bottom nut do not fit the stanchions.
The stanchions are new and numbered 4007 which should be correct. I bought a pair of top nuts no 4258 and they dont fit either so my thoughts are that the stanchions which were presumably bought by the previous owner as replacement are wrong and for a later model. I have a 1964 A65 with later forks and conical hub fitted and the top nuts for that fit the new stanchions but unfortunately I dont know the year of the forks.
Did the top thread change during the production run and if so what is the part no of the top nuts and damper nuts to fit the later models

 

The conical hub will only fit the conical hub forks. The earlier ones and the later disc ones do not interchange although the stanchions are the same size so could interchange as a complete assembly, which is what I have on the A65
The forks are the correct forks, it is an oil in frame. My question was "what year did the threads change on the fork legs", Triumph changed threads from cycle to unified over a number of years in a bloody nuisance piecemeal fashion so without a library of parts books I dont know when the forks altered.
On another note the frame no gives 1970 and is oil in frame so a very early one. The engine number gives late 69 but as years changed at the Earls Court show it could be a 70 engine manufactured in late 1969. Again Triumph changing things piecemeal.
Another piece of info has come to light. The fork stanchions were shortened in about 73 so theoretically there may be early thread, late thread, short or long. Which came first shortened stanchions or altered thread?

 

Age is a number. After a few pints I am a teenager but in the morning I am 115