Joined: Jul 2015
Posts: 7,498
Likes: 3,301
From: NW Oregon
Bikes: 1982 Trek 930R Custom, '91 Diamondback Ascent w/ XT, XTR updates, Fuji Team Pro CF road flyer, Specialized Sirrus Gravel Convert, '09 Comencal Meta 5.5 XC, '02 Marin MBX500, '84 Gitane Criterium bike
what derailleur? there are a couple thread sizes in japanese/metric that are fairly common, but anything french or italian is a best-guess situation.
got a measuring caliper handy?
is there a well-stocked hardware store, or a Co-op bike shop, nearby?
the hardware store can help pin down the thread size/pitch...
i have TWO small parts drawers filled with them... and dig into the parts-only ders box sometimes too...