A directional drilling tool comprising: a variable position stabilizer; an outer sleeve having an eccentric bore; an inner sleeve having an eccentric bore which is disposed inside the bore of said outer sleeve, wherein the radial position of said stabilizer may be adjusted by relative rotation of said outer sleeve and said inner sleeve; a drive shaft having a longitudinal bore which is disposed inside the bore of said inner sleeve; and an eccentric coupling (25, 26) in communication with said outer sleeve and configured to transmit torque to said outer sleeve to adjust the position of said variable position stabilizer comprising: a first coupling sleeve (22,85); a second coupling sleeve (23,86); a first complementary tab and groove set (30, 31, 100, 101), comprising at least one pair of tabs (30, 100) and one pair of grooves (31, 101), which may transmit torque between said first coupling sleeve (22, 85) and said second coupling sleeve (23,86); a third coupling sleeve (24, 87); and a second complementary tab and groove set (32, 33, 102, 103), comprising at least one pair of tabs (33, 103) and one pair of grooves (32, 102), which may transmit torque between said second coupler sleeve and said third coupling sleeve (24, 87) wherein the grooves (32, 102) of said second complementary tab and groove set are orthogonal to the grooves (31, 101) of said first complementary tab and groove set. a variable position stabilizer; an outer sleeve having an eccentric bore; an inner sleeve having an eccentric bore which is disposed inside the bore of said outer sleeve, wherein the radial position of said stabilizer may be adjusted by relative rotation of said outer sleeve and said inner sleeve; a drive shaft having a longitudinal bore which is disposed inside the bore of said inner sleeve; and an eccentric coupling (25, 26) in communication with said outer sleeve and configured to transmit torque to said outer sleeve to adjust the position of said variable position stabilizer comprising: a first coupling sleeve (22,85); a second coupling sleeve (23,86); a first complementary tab and groove set (30, 31, 100, 101), comprising at least one pair of tabs (30, 100) and one pair of grooves (31, 101), which may transmit torque between said first coupling sleeve (22, 85) and said second coupling sleeve (23,86); a third coupling sleeve (24, 87); and a second complementary tab and groove set (32, 33, 102, 103), comprising at least one pair of tabs (33, 103) and one pair of grooves (32, 102), which may transmit torque between said second coupler sleeve and said third coupling sleeve (24, 87) wherein the grooves (32, 102) of said second complementary tab and groove set are orthogonal to the grooves (31, 101) of said first complementary tab and groove set. a first coupling sleeve (22,85); a second coupling sleeve (23,86); a first complementary tab and groove set (30, 31, 100, 101), comprising at least one pair of tabs (30, 100) and one pair of grooves (31, 101), which may transmit torque between said first coupling sleeve (22, 85) and said second coupling sleeve (23,86); a third coupling sleeve (24, 87); and a second complementary tab and groove set (32, 33, 102, 103), comprising at least one pair of tabs (33, 103) and one pair of grooves (32, 102), which may transmit torque between said second coupler sleeve and said third coupling sleeve (24, 87) wherein the grooves (32, 102) of said second complementary tab and groove set are orthogonal to the grooves (31, 101) of said first complementary tab and groove set.