Somehow the shaft that connects the two outboard bearing cups on my Truvativ GXP bottom bracket has cracked at one end, and I'd like to replace it before sunday. I doubt my LBS carries truvativ, so can I replace it with like an Ultegra cup set? or is the inner diameter of these model/brand independent. I know shimano and the GXP cups all use the same wrench and groove pattern, but not sure about the other attributes