There is something about some set-neck 4000's that I don't understand. The neck meets the body at a different angle side-to-side than on a neck-thru 4001/4003.
As a result, the upper horn is higher in relation to the body.
To demonstrate, let's look at part of a page from Ric's 1975 catalog, which has a set-neck 4000 and a neck-thru 4001.
I'll draw a red rectangle, perpendicular to the strings, so that you will see what I'm talking about.