I owned a Limited prior to purchasing my SRT-6 and I thought the same thing and checked out the under side my limited hatch to see about a swap.

On the SRT-6 - there is no motor, hinges, drain tubes, wiring harness, dash switch and my guess is no relay commands from the computer to activate the wing at proper speed. Also the piece that "would be the wing" on the SRT does not have the molded edge.

Like other SRT owners - the fixed wing grew on me - plus its one less thing to break down.