So, while looking at replacement driveshaft, Ford decided to use a different length depending on engine/trans, etc - I get that. But also depends on single or dual rear wheels - I kinda get that, maybe there is a different spacer from trans to transfer case for the long wheelbase trucks and GVW (mine is crew cab long box 1 ton single rear wheel) - but it also seems likely there is a length change depending on color, what mirrors, radio type, if there is a vanity mirror, type of rear bumper, color of interior, cigarette lighter, etc.... Grrrrrr