Daytona Pinion Support and Yoke
Ford describes the part used to support the rear end pinion gear as the "driving pinion bearing retainer and bearing cup assembly", identified by basic part number 4614. It's more commonly called a "pinion support". The pinion support used on all 1968 - 1970 Ford Mustangs equipped with a 9" ring gear and 31-spline rear axle shafts (which just so happens to include Mustangs equipped with 428 CJ and SCJ engines) is often called the "Daytona" pinion support.