I have a diff which looks like a escort english diff, but its bigger. Its an lsd or gripper/locker with ford casting marks on. It looks to have 25 spline side gears for the halfshafts and an oil fill plug on the side of the diff unlike the english one which is on the rear of the axle.
It may have been used in a stockcar at some time but not sure.
Some pics, english diff on the right.