The oproblem regardign stretches as I am given to understand it is that some are older airframes stretched with a Plug inserted, whilst others are entire new airframes that completely replace the shorter one. The mechanices along with longer wiring looms are put into the new airframe, but in either case the airframe is zero timed again. BATC has made it to the end without the stretch which I know is not desireable to be in if slingloading as the centre of gravity is not as comfoprtable as on the shorter airframe.