Dutchy50,

When I put the Robostruts in my Hangar 9 Miss America, all I did was install the retract into the wing in the "gear up" position and then measured the distance from the end of the retract unit itself to the center of the wheel well. I also found it helps if you file flat spots on your 3/16" strut wire, it helps to really tighten up the set screws.

Good luck with your Mustang. I hope I helped you out.

David