housing modules 310 disposed within openings 312 within the wall of housing 302 and intermediate portion of rotating shaft 300 disposed within housing 302 fig4 c illustrates a circumferential cross sectional view of housing modules 310 and their orientation fig4 d illustrates head end 304 of rotating shaft 300 referring to fig4 a box end 306 couples to rotating shaft 300 in any suitable manner in a particular embodiment box end 306 is formed integral with rotating shaft 300 box end 306 has internal threads 316 that function to accept external threads 317 of saver sub 308 in order to couple saver sub 308 to box end 306 saver sub 308 functions to couple drilling tool 40 thereto and protects box end 306 from damage arising from repeated threading unthreading of drilling tool 40 steering system 212 according to one embodiment includes a spring member 402 having a bearing surface 401 a pair of mounting pins 406 coupling spring member 402 to housing 302 and a piston 404 generally steering system 212 functions to steer drilling tool 40 in a desired direction when arched spring member 402 of steering system 212 is actuated radially by a respective piston 404 such that bearing surface 401 applies a force to the wall of well bore 32 although bearing surface 401 may have any suitable profile including a flat surface bearing surface 401 preferably has a curved profile that substantially matches the profile of the wall of well bore 32 so that an evenly distributed load may be applied thereto spring member 402 is.