I have to completely disagree with Roses and any speculation that William Hollenbaugh was involved in this disappearance of Kathy. I live in the area of Shade Gap and Burnt Cabins. I have family that knew of Hollenbaugh, and family that searched for P.A.B. and Hollenbaugh after her abduction. Most people I've talked to have said Hollenbaugh, though weird and distant, wasn't exactly a criminal mastermind, and it's pretty much known that he steadily worked for the locals in the area up until P.A.B's abduction, getting to and from on a bicycle.
A mountain-man, sure, but no mastermind of crime. As a matter of fact, he was immediately suspected in her disappearance (P.A.B) as he hadn't shown up to feed the livestock of the farmer, whose land his shack sat on, which was weird to them because was known to be dependable. They said that if he'd fed the animals after her abduction, and hid her somewhere close, he'd have probably never been suspected in Peggy's abduction. Additionally, he didn't just sneak off with her while she was alone, he kidnapped her at gunpoint in front of all of her siblings, wearing several layers of clothes, a cheek filler (to make his face rounder) and big goggles to disguise himself.
His making it to Tyrone (30 miles) via bicycle and rails is possible, though I highly doubt it. He moved to the area around 1962, and he was committing crimes in the area up until P.A.B's abduction in 1966. Most of these crimes involved "peeping Tom" type incidents involving grown women, or larceny. Shortly after Kathy's disappearance (less than a month) Hollenbaugh was linked to a shooting of a local man who approached a trespasser on his property at night. The shooter was thought to have been spying on the man's wife at the time. I've never heard stories of him ever harassing little girls or eyeing them, etc. Kathy's case doesn't fit his M.O. as far as I can see. All of his crimes also involved firearms (long guns), which had someone (around the time of Kathy's disappearance) seen a man traveling the rails or a bicycle with a long gun, I'm sure it would have been mentioned to L.E.O's. Peggy was 17 when this happened, and not little and defenseless.
IMHO, Hollenbaugh had more than enough people to harass in Shade Gap and Burnt Cabins, and no need to go to Tyrone for an abduction of a child. He was close enough to McConnellsburg, Huntingdon, and Mt. Union if he were looking for a larger town to kidnap a child. Roses, if you want to front the bill, I can take the handler and his/her cadaver dogs right to where his shack used to be. It's only several-hundred yards from route 522. Not being rude, but this throws the case in a totally different direction. I believe the answer lies with someone in or very close to Tyrone.