I received my new Shimano UN 54 bottom bracket yesterday and went to install it today. It was labeled 68x113mm. I pulled to old busted one out, labeled 68x113mm, installed the new one, then put the cranks back on. Instantly I noticed the crank was much closer to the BB shell then before. I pulled to whole thing apart and measured both spindles. The old one measured a correct 112.5mm, but the new one measured out to be 109.5mm! Yes, I measured twice.
I'm sending the new Shimano one back and have ordered a Stronglight JP400 for a replacement.