No, not all of them are "unique", some are but many sold in the US were compatible with Campy spindles and other Campy knock-off brand spindles. However, with a Shimano JIS spindle you may experience 'class B' or lower fit...try one and see! If it fits without bottoming out or too-little interface contact then...you're good to go in my book.And if you have the option try a Phil Wood BB, those used a "hybrid" spindle taper that might be right in the sweet spot!