8 3/4 Rear Disc Brakes

Going to look at a car in the morning that has a disc brake set up on an 8 3/4 under a 64 barracuda. owner does not know the brand of it. any one have tips on how to determine what brand the kit is? this might be a tough one to ask with out knowing the brand, but if they dont have a parking brake set up, is that a pricey addition?

thanks.