A few points where P-8B varies from commercial 737.
Forward and aft fuselage bomb bays mandate pressurization at the floor deck. Also I think there is/are 1 or 2 added belly fuel tanks. Also, don't forget wing store stations and air refueling provisions. Also on board com/nav avionics, surface/subsurface surveillance equipment, observation windows, sonor bouy storage/ejection, radar warning, chaff/flare, other countermeasures, Etc.
P-8 fatigue spectrum is far more severe... low level during surveillance mandates far tougher structure: materials, fastening practices, etc. Think hurricane hunter.
Oceanic environment mandates rigorous sealing and corrosion protection for structures, systems, engines, etc.
Also the Acft has mandatory nuclear warfare protections that are very rigorou.
Regards, Wil Taylor
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