its called a 'parking brake strut bar'. buicks and caddys 63 -70 with 12'' brakes. brake width doesnt matter. closest i can come up with by looking at the picture is a c/q SB21129, circa '94 catalog. btw, you can drive w/o it. just no p/b.
I am in the process of swapping my front drums for discs, they are from a 72 skylark. you can have em if ya want em. I'll need a address. PM me:3gears: