Who owns the 68 Plymouth Barracuda Super Stock mule car ?

Not really. Cars back then were designed 2-3 years in advance.
The Abody Super Stock project didn’t get rolling until Fall/Winter 1967. That well into the 1968 production year. No reason for 1967 Barracudas to be laying around.

But the real deal is the Super Stock project notes say it’s a 1968. Even lists the lot/tracking number for it.
Absolutely correct about early designs. The 70 Barracuda design was started somewhere during '67/'68 if I remember correctly.