A gas turbine engine, comprising: a turbine rotating via a gas turbine engine shaft; a tower shaft operably connected to the gas turbine engine shaft configured as a power takeoff of rotational energy from the gas turbine engine shaft; and a power transmission; the gas turbine engine characterized in that the power transmission comprises: an input shaft; an output shaft; a plurality of gear ratios (66a-d) to transfer rotational energy from the input shaft to the output shaft to drive the output shaft at a selected output shaft speed; and a plurality of clutches (74a-d), each clutch disposed at a clutch lay shaft (68a,b) of a plurality of clutch lay shafts and configured to control selective engagement of only one gear ratio of the plurality of gear ratios, wherein each gear ratio (66a-d) comprises: an input gear (70a-d) disposed at and rotatable with the input shaft; and a ratio output gear (72a-d) disposed at and rotatable with a clutch lay shaft of the plurality of clutch lay shafts; wherein the ratio output gear (72a-d) is selectably engagable with one of the plurality of clutch lay shafts via engagement of the respective clutch of the plurality of clutches (74a-d) disposed at the clutch lay shaft (68a,b); and wherein the input shaft is operably connected to and driven by the tower shaft. a turbine rotating via a gas turbine engine shaft; a tower shaft operably connected to the gas turbine engine shaft configured as a power takeoff of rotational energy from the gas turbine engine shaft; and a power transmission; the gas turbine engine characterized in that the power transmission comprises: an input shaft; an output shaft; a plurality of gear ratios (66a-d) to transfer rotational energy from the input shaft to the output shaft to drive the output shaft at a selected output shaft speed; and a plurality of clutches (74a-d), each clutch disposed at a clutch lay shaft (68a,b) of a plurality of clutch lay shafts and configured to control selective engagement of only one gear ratio of the plurality of gear ratios, wherein each gear ratio (66a-d) comprises: an input gear (70a-d) disposed at and rotatable with the input shaft; and a ratio output gear (72a-d) disposed at and rotatable with a clutch lay shaft of the plurality of clutch lay shafts; wherein the ratio output gear (72a-d) is selectably engagable with one of the plurality of clutch lay shafts via engagement of the respective clutch of the plurality of clutches (74a-d) disposed at the clutch lay shaft (68a,b); and wherein the input shaft is operably connected to and driven by the tower shaft. an input shaft; an output shaft; a plurality of gear ratios (66a-d) to transfer rotational energy from the input shaft to the output shaft to drive the output shaft at a selected output shaft speed; and a plurality of clutches (74a-d), each clutch disposed at a clutch lay shaft (68a,b) of a plurality of clutch lay shafts and configured to control selective engagement of only one gear ratio of the plurality of gear ratios, wherein each gear ratio (66a-d) comprises: an input gear (70a-d) disposed at and rotatable with the input shaft; and a ratio output gear (72a-d) disposed at and rotatable with a clutch lay shaft of the plurality of clutch lay shafts; wherein the ratio output gear (72a-d) is selectably engagable with one of the plurality of clutch lay shafts via engagement of the respective clutch of the plurality of clutches (74a-d) disposed at the clutch lay shaft (68a,b); and wherein the input shaft is operably connected to and driven by the tower shaft. an input gear (70a-d) disposed at and rotatable with the input shaft; and a ratio output gear (72a-d) disposed at and rotatable with a clutch lay shaft of the plurality of clutch lay shafts; wherein the ratio output gear (72a-d) is selectably engagable with one of the plurality of clutch lay shafts via engagement of the respective clutch of the plurality of clutches (74a-d) disposed at the clutch lay shaft (68a,b); and wherein the input shaft is operably connected to and driven by the tower shaft.