I read several decades ago about how the 747SP's trailing edge flaps were substantially redesigned from those of the "original" 747-100/-200s. The images on the 747SP Wikipedia page clearly show what appears to be an unslotted Fowler flap - contrast with the triple-slotted Fowler flap of the 747-100.
Why the major re-design?
Related sub-question: The Wikipedia page also mentions "... the SP's heavy wings" as one of the factors contributing to its cancellation. But, the SP had the same wing (modulo the trailing edge flaps) as the -100/-200. How could its wing be considered "heavy" in this context? (I'm thinking maybe it has to do with moments of inertia and/or size relative to the fuselage, but hopefully someone else here can clarify this.)
Wikimedia Commons (from the Wikipedia 747SP page)