surely there's some one in here or who knows someone who's a transmission expert...........i wonder if theres ever been that question asked to a magizine or someone with an absolute knowledge of exactly what it does internally.........seems like the closest i saw to a legit technical explanation was that when you put it back into first it re-routes fluid or increases pressure in an area that effects a drum held on by a snap ring and can over pressure it and blow...regardless though, i'll stay on the safe side,,,,,,,would"t even be an issue if ford could have made a seprate detent for second or used an in handle o'd switch.....lol...friggin ford....gotta luv'em though.