Joined: Jan 2008
Posts: 23,645
Likes: 1,109
From: Mans of NC & SW UT Desert
Bikes: 86 Katakura Silk, 87 Prologue X2, 88 Cimarron LE, 1975 Sekai 4000 Professional, 73 Paramount, plus more
If you don't have the drive side BB off, don't rule out Swiss threading. Same size as french, but left hand thread on the drive side.
I routinely pick up beater Motobecanes solely to pick up Japanese Swiss BB, Japanese forged french sized stems, and nice Suntour RDs. Different than the other french manufacturers, I have found Swiss BB on Motobecanes spanning many years, from the mid to late 1970s to 1982.