All the breather parts are interchangeable....The only difference between the breathers fitted to the crank case and those located in the timing cover is the thread that the breather pipe nut screws onto....On engines with the breather in the crank case the thread is 7/16" x 20tpi Cycle Thread, on breathers fitted to the timing cover the thread is larger...1/4" BSP...
The threads in the crank case and the timing cover are the same...
There are some detail differences over different years of the fitting that retains the Tufnol 'flap valve' into its housing but all of these are interchangeable....Ian
Thanks Ian, the issue is not the breather but the crank case threads between the two. The "new" one is completely stripped down. Now I Will use the parts from my "old" crank case.
They have the same part number, but I want to be sure.