Construction differences on Nelson/Miller platform benches  

Hi all. . .. . . first post here. My wife and I just purchased a wonderful George Nelson slatted platform bench by Herman Miller.  It's a beautiful piece. In looking around at other similar benches on the web in the effort to learn more about them, it is becoming clear to me that Miller changed their manufacturing methods quite a bit over the years.  I'm wondering if these changes are due to the ages of the pieces or possibly the place of manufacture, or possibly something else entirely. Among the significant differences I've noted are these: 1.  Dowels versus nails on the middle support slats.  It seems that the majority of the the Miller/Nelson benches have dowel pegs down the middle and around the outside edges.  But, strangely, some have TWO sets of dowels down the middle supports, while others just have one.  In addition, instead of dowels, some have two sets of very small nails, deeply inset into the wood along the middle supports.  Age doesn't seem to be the sole determining factor of these differences, as some of those with the tiny nails are marked (as is ours) with the rounded foil label (affixed, in our case, with the same tiny nails used in the construction of the piece), while others with the same construction have the round emblem label. 2.  Screw arrangement on the legs.  Most benches have the legs screwed in with the two sets of screws aligned as two parallel slashes / and /, whereas others have the screws arranged with the screws at an angle, such as \ and /.  3.  Screw arrangement by slat.  In some cases the legs are attached to slats two and three (counting in from each edge), whereas in others they are attached to slats three and four. Does anyone have any idea why they changed things so much on a product that, to me at least, would seem to be very well standardized?  There may, of course, be other differences I have yet to note. Thanks for your help. Stephen Pruitt, Ph.D.Kansas City