I can't believe that manufacturers are not honestly providing truthful information. McGaughy states they never heard of front track width increasing with the use of their spindles. BellTech states that there will be no axle shift when using their lowering kit.
While I'm no expert by any stretch of the imagination I know how to research things. Sometimes a little too late and not enough.
There is plenty of talk on multiple forums regarding lowering / lifting trucks with panhard rods / track bars and the effect on axle positioning when changing the truck height. Many different fixes also can be found from drilling new holes in the factory frame mount to making the panhard rod adjustable or purchasing an adjustable one. I found a simple picture that will maybe help explain or illustrate the movement that will be experienced when lowering without correction. McGaughy knows this which is why they provide a relocating bracket with some of their kits.