Originally Posted by hazetguy

Note: I am by no means an expert, I have limited experience, and I could very well be doing something wrong, but....

I removed the oe equipped Mistral cranks and bottom bracket off my Trek 660 when I was switching over to Shimano 600/6400/Tri-Color. When I tried to install the Shimano cranks on the Ofmega bottom bracket axle, it would not go on far enough for proper chainline. Ofmega axle was 118mm wide.
I wound up switching the bottom bracket to a Shimano UN55 with a 113mm wide axle, and the 600/Tri-Color crank fit on and aligned properly.
It seemed to me like the Mistral cranks and/or Ofmega axle had a different taper which allowed the cranks to go on further.