to withstand the applied external forces the diameters 14 b and 14 d function as pressure sealing surfaces and are also designed and proportioned to effect a balance of hydrostatic pressure forces applied to the load rod 14 the diameter 14 c is sized to provide mechanical shoulders as a means to transfer the external tension and compression forces the internal diameter 14 e provides for mechanical clearance and the diameter 14 f provides passage for electrical wiring and optical fibers the seal body 10 see fig2 and fig4 functions as an extension of the lower housing 15 and provides a seal for the upper end of the load rod 14 and the top sub 1 the critical design features of the seal body shown in fig4 are the axial bores 10 a 10 b 10 c the two external parallel flats 10 d the two external windows 10 e which are perpendicular to the two flats and the o rings 10 f and 10 g the bore 10 a is sized to clear the outside diameter of the pull rod together with the o rings 10 f and 10 g the bores 10 b and 10 c are proportioned to effect a pressure seal on the pull rod diameter 14 d and the top sub diameter.