You're mentioning 2/3 different types of bottom bracket here. 75DD is external so won't be 103mm, its just two cups and the axle is on the cranks. 75s are square taper. and then there's octalink.
@PhilDAS started
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You're mentioning 2/3 different types of bottom bracket here. 75DD is external so won't be 103mm, its just two cups and the axle is on the cranks. 75s are square taper. and then there's octalink.