Buffalo Trace makes a lot of different bourbons but they only have a few mash bills. Age and placement in the warehouses determine the rest. Their #1 mash bill is a low-rye bill (less than 10%) and makes some big names: Eagle Rare, George T. Stagg and Stagg Jr., Colonel E.H. Taylor, the eponymous Buffalo Trace, Old Charter and McAfee's Benchmark.
Benchmark Old No. 8 bourbon was created by Seagram's in the late 1960s as a luxury brand and was originally named Benchmark Bourbon. It was produced at the Four Roses distillery when Seagram's owned it. The brand name was purchased by Sazerac in 1992 and McAfee's was added to the name in honor of the McAfee brothers who surveyed a site just north of Frankfort in the late 1700s.