The "walnut" stripe (actually a strip of shedua) started in spring of 1972, so that's not an indicator to look for before that time. Later in 1972, the factory started making the 4000 bodies from a two-piece slab and cutting a pocket for a set neck. The necks featured the shedua stip, but the bodies, of course, did not. The Mapleglo example in the photo above is a neck-through, and as Granny observed, has the grain of the body wings interrupted by the center assembly.
So from, say, the middle of 1972 until the end of production of the single-pickup 4000 in the early '80s, you would have a set neck with shedua strip and a two-piece body – the "seam" would be smack in the middle of the body if you can see it. Also, the "4001S" of that time period shared a common chassis with the 4000. Interestingly, Rickenbacker price lists didn't show "4001S" at all until AFTER the introduction of the 4003/4003S. Lots of interesting tidbits in the book!