I have a 1985 Bianchi Stelvio with a worn bottom bracket. The shell width measures 68mm, but the threading appears to be Italian? Both left and right sides are right threaded, and when I tried an English bottom bracket I had lying around (on the drive side) it was a bit too small.
Does this mean I have a French threaded bottom bracket, as Sheldon Brown's site might suggest? The cranks are ostensibly Ofmega Brilliante, according to a period review of the bike. Neither the cranks nor the bottom bracket are marked in any way. Zilch. I've read that Ofmega spindles are not compatible with other makes so I've considered buying a vintage Campy crankset to go with a vintage bottom bracket, but I'm not sure what would work.
I suppose I could also go modern with a cartridge BB, but my preference is to keep the bike period if possible.