What brand is the crank? SRAM is the only crank that uses GXP and the non-drive side is only 22mm vs 24mm for the rest of the spindle. Shimano and others use a spindle that is 24mm for the entire length. Your picture looks like about a 2mm difference between the splined ends, which means it is probably not a 30mm spindle. You probably need a Shimano or FSA external BB for that crank.