It is the '50's rounded neck (I think it's either the same or just like the '59 rounded), which is the one on most of the '68 RI's I've seen. I believe that only the Guitar Center '68 RI's have the '60's slim neck. Why the '50's rounded neck? I guess it has something to do with Gibson resuming the production of the Les Paul Standard model in 1968, whose neck resembled those during the 1958-1960 run. But on that question, I defer to those who know Gibson history well.