747SP Rear end
I wouldn't call the rear end of a 747 SP an example of area ruling. The reason for the indentation is (in my view) purely the result of the removal of a large part of the tapered afterbody of the aircraft when they designed the SP. The difference in width of the fuselage sections that then needed to be grafted together necessitated the indentation. The only other option would have been to redesign the entire tail section and Boeing obviously didn't want to pay the cost of that.
Ironically the 747 does posess a very good example of (probably not fully intentional) area ruling and its on the other side of the wing. The upper deck just slopes down to the normal fuselage height at the point where the wings start to sprout from the fuselage, this has the aforementioned effect of keeping the total cross section area more or less the same, or at least increasing it gradually.