Early 88's had one action bar but the current one's have 2, just like the 500 does. The forarm and rails on the current production guns are the same except for the differences to accomodate the plastic vs. wood forends.
Call Mossberg and they will tell you that these are made in Texas, not Mexico.
Like I said earlier I had one of each apart on the bench and cleaned them both at the same time. Except for the 2 differences notes above the 2 guns I had in my hands were identical, right down to the tool marks on the parts. I would be willing to bet I could toss all of the parts in a box and mix them up and not be able to tell which went in what gun.