Help identifying differential

I thought that I'd purchased an open differential with 4.11 gears for my bronco ('68, factory 9" rear end), but when I backed out of the driveway, and turned on to the street, the tires were chirping. Anytime I take a tight corner (street use, sees no dirt), the tires chirp.

Any help identifying what I have is appreciated.

Part #'s C6AW 4206

I pulled it back out to assess what I had, and took these pics: