I bought one of the 1970 Mustang brochures that the dealer would have had in the showroom that lists the different models. I noticed that the twist lock's on the Mach 1 in the book are actually different than the ones that came on the cars. Mine have 3 raised places and are not flush with the retainer. The ones in the book have a raised bar in the middle and look to be flush with the retainer. Anyone have the scoop on this.Did they change before production run?