Originally Posted by
TenGrainBread
"DS" is DriveSide. He's saying you can use a BB spacer to add some shell width to the driveside.
I would check the shell width with a reliable caliper before messing with spacers. Chances are it's 68 and your plastic caliper just sucks.
For some reason my '74 Raleigh Comp has a 66odd shell. I noticed that the NDS cup (on a replacement Shimano that had been installed) was spaced out from the shell, but I could not tighten it further. So I measured the shell, and it's narrow.