I've seen photos of the 601, 650, 700 and Hanno pipes in the "crude" (welds showing)...The baffle spacing is noticeably different between each of the pipes...I'll try to find those photos if I can and post them later...

edit:
Posted pic below...

To me the pipe length & baffle spacing is what differentiates the the pipes...I'm sure there are both smooth and crude pipes in all of them...I'm guessing a little but..I believe the smooth-vs-crude may have come as a vendor or manufacturing change at some point??

Like I mentioned above...My 1987 Hatori catalog shows the "smooth" version on the cover...Then all of my 401 and 650's are the crude version which were bought 1990 or later...