one embodiment of the present invention is a unique gas turbine engine . another embodiment is a unique gas turbine engine main engine rotor . still another embodiment is a unique method for assembling a gas turbine engine main engine rotor . other embodiments include apparatuses , systems , devices , hardware , methods , and combinations for gas turbine engines and gas turbine rotors . further embodiments , forms , features , aspects , benefits , and advantages of the present application shall become apparent from the description and figures provided herewith .