If your Barracuda has fixed calipers with 4 pistons each it is almost certainly the Kelsey - Hayes system. Only exception would be a very early drum car refitted with Girling calipers - I think that was only for rally and development purposes, never production.
Several companies machine and brand the replacement disks. Bendix, Borg Warner, Centrix (under several names) and possibly Wagner. As best I can tell, currently the raw castings come from one supplier.
You want the ones with best machining. Make sure the 'hat' is machined otherwise the casting may kiss the caliper or piston boot every rotation.
I doubt a vibration relates to the disk itself. That said, the originals and old stock replacements were sold as hub-disk assemblies and you will see little weights in the rotor vanes. It seems likely the factory was balancing them, but I've never heard anyone say they had an issue.
Check wheel bearings, make sure there is no play and check the wheels for balance. More likely a wheel lost a weight.
With a dial caliper, you can check runout. There's photos in the various MTSC booklets about those systems -
Master Technician Service Conference - Chrysler's Training for Mechanics The shop manuals are great - you can buy or download digital versions.
Pads are D11, same as used on several years of Mustangs and a few Corvettes. Many choices in lining material are available.
