why would Ford mark a drive line that will never be ran in and then removed... I think as with all their other "paint markings" it is more of a code for final assy. or marking different parts for different apps.
yall are full interesting information. The history of "why" can be facination. Thanks for sharing, i enjoy the read.
I will go out on a limb on this one. Maybe there wasn't enough room to add the spline and keep the splines evenly spaced?