Piping Rock is outstanding but hardly "pure Macdonald/Raynor." As some have alluded to, Pete Dye lengthened the course in 1985 and made a couple of changes, with me supervising the construction work. Rich Spears, the superintendent, has made a couple of further tweaks.
It's been a long time, but I think that the back tee on 17 was there when we started -- it had already been lengthened by someone else. We chopped off about 30% of the area of that green to make it a bit tougher, and dug out the bunkers around the green MUCH deeper. [The front bunker is perhaps ten feet deeper than Macdonald had it.]
I don't know who changed the 15th green or when, but we didn't touch it. Those "snake mounds" running through the green are a delight -- never seen anything else quite like them.