'66 Barracuda rear axle question

They could be playing a word game with you. Did they say the parts are from a national brand or that the company that made the part is called National? The company National Seal makes nice seals and has been around forever but I've never heard of them making bearings. Timken, SKF, Bower/BCA are bearings I've had good luck with in the past...C/R (Chicago Rawhide) is another good seal company.