450X - Original T-Rex model with grey (soft) plastic frames and short boom. Used mechanical mixing for cyclic and collective. 315 mm blades only.
450XL HDE - Upgraded X with longer boom to support 325 mm and 335 mm blades. Changed plastic to black, better plastic.
450XL CDE - Same as XL HDE but used electronic CCPM mixing for cyclic and collective control. Servos still actuated the swash via bell cranks.
450SE - Major change to direct servo to swash eCCPM mixing. Carbon fiber frames, CNC aluminum for the head parts, tail case, bearing blocks. The 430X motor was included.
450SA - ARF (95% assembled) version specific to Horizon Hobby. Fully assembled, with frames based on SE layout, but made of aluminum. Head parts, tail parts, and bearing blocks were plastic like the XL plus the 430X motor.
450S - kit version of the SA with choice of carbon fiber or aluminum frames. Plastic head, tail and other parts. A later GF version featured fiber glass frames.
450SE V2 - Align updated the rotor head to take a 4 mm (vs 3 mm) spindle shaft and thrust bearings in the main grips, changed the frame layout to change the battery tray angle and to mount the gyro under the boom block. The tail servo mount was changed to fit the mini servos that most people are using versus the older versions assuming micro servos. The 430XL motor was included.
Later ‘V3’ was offered as a series of upgrade parts, but not a complete helicopter.
450 Sport - improvement on the V2 design, sometimes called ‘V3’. It uses the rotor head construction of the new 450 Pro with a slightly different appearance, but keeps the belt drive, tail servo and double-layer main frame of the V2. The frame is narrower than the V2, the metal connectors are enforced and a new tail mechanism is in place. In the align kit a new 450M outrunner motor is included.
450 Pro - Widely new design, tail rotor is now driven by a torque tube instead of a belt, and a larger tail servo mounted in the frame. The head is modified and uses the more agile liver mechanics like the ‘V3’, the frame design is completely different and encloses the servos between the frame plates. Align bundled a new 450M outrunner motor.
