Originally Posted by
JohnDThompson
Metric thread. There's no clear picture of the markings on your fixed cup, so I can't distinguish between "French" and "Swiss."
French, if the fixed cup is right-hand thread. Swiss, if the fixed cup is left-hand thread.
It's French threading. Shimano didn't catalogue Swiss fixed cups in 1984. 35 x P1 is the standard Japanese marking for French thread. Japanese manufactured Swiss fixed cups, when you can find them, are typically marked 35 x P1 S1.