I have a 1985 schwin high sierra that was given to me and I need to replace the bottom bracket. It is a sugino and it only has markings on the spindle, 3U, D-9, SCM. I don't know what they mean and Sheldon browns website doesn't either. I measured a 68x127. I want to know if I can replace it with a modern version that would fit and if the markings have anything to do with it?
Sugino and Shimano have different crank tapers... older Sugino cranks (ISO) will sit 4.5mm farther outboard on a Shimano spindle (JIS) while a Shimano crank (JIS) on an older Sugino ISO spindle will sit 4.5mm farther inboard.
If it is a newer Sugino crank that is JIS a 127mm bottom bracket is the needed replacement, if it is an older ISo crankset and you use a Shimano / JIS bottom bracket you need to adjust by using a spindle that is 4.5mm narrower (approximate).