Integrated circuit die stacks having a first die mounted upon a substrate, the first die manufactured to be initially identical to a second die with a plurality of through silicon vias (‘TSVs’), the first die personalized by blowing fuses on the first die, converting the TSVs previously connected through the blown fuses into pass-through vias (‘PTVs’), each PTV implementing a conductive pathway through the first die with no connection to any circuitry on the first die; and the second die, manufactured to be initially identical to the first die and later personalized by blowing fuses on the second die, the second die mounted upon the first die so that the PTVs in the first die connect signal lines from the substrate through the first die to TSVs in the second die.