Apart from the obvious 1/2 inch shift of the neck pickup, with which we're all familiar, I notice that on the 4003 version the "lobe" of the pickguard is slightly more bulbous, with the controls spaced a little differently.
What I'd like to know is this: what was the train of thought/design that led to this slight change of shape? Was it perhaps felt necessary to provide a slightly larger control cavity on the 4003 - and if so, why?

